List of leaks
A leak is a revelation of information about a game that has been released prematurely, especially without prior permission to release such information. While game developers go through great lengths to prevent leaks from occurring, it is very common for games to have important information leaked out before being officially revealed.
Leaks can either be done intentionally via third-parties for a variety of reasons, such as increasing publicity for a game or for malicious intentions, or unintentionally via oversights that can appear in officially released media.
Due to the lack of a developed infrastructure on the Internet prior to their releases, neither Super Smash Bros. nor Super Smash Bros. Melee had leaks of notable proportions prior to their release. Starting with Super Smash Bros. Brawl, the significantly more developed Internet of the 21st century made leaks much more common, particularly in pre-release hype. A large amount of them, however, tend to be invariably sketchy, with the contents of these leaks often being radically different from what is actually in the game. The large amount of rumors that start as a result makes it very difficult to pinpoint which are actual leaks before their contents are officially confirmed; this is especially a concern with leaks that are purely text, as the modes of discourse with these kinds of posts tend to differ very little. In spite of this, a varying number of real leaks can emerge, though they have been historically met with backlash upon their initial posting, often either for being deemed too outlandish to be true or for "parroting" claims made by other posts.
Super Smash Bros. Brawl leaks
As stated prior, the pre-release period of Brawl began a trend in which posts regarding unrevealed content would inundate forums and message boards. Despite the massive amount of fake "leaks", there were a few real ones, from both slipups from those directly involved in Brawl and from people who managed to obtain information about the game. Upon Brawl's release in Japan in late January 2008, leaks could then be cross-checked with the actual game; actual screenshots and videos of the game provided considerable information to players outside of Japan, most of which had not yet been revealed by the DOJO!!.
ChaosZero was a user on GameFAQs that obtained information about Brawl from an unknown source, and posted what he knew on GameFAQs on October 2007. His information leaked the following:
Despite leaking 100% correct information, ChaosZero was treated as a troll, and was largely derided by GameFAQs users and disbelieved in general. However, after the Dragoon item was confirmed, his reputation became more positive, and he earned the nickname "The Dragoon Prophet."
NyaseNya was a user on SmashBoards with an infamous reputation as a troll obsessed with Peach. Despite his reputation however, he obtained legitimate inside information of Brawl, and posted it in a thread on SmashBoards. His information leaked the following:
NyaseNya also leaked Sonic and the exact date he would be revealed on. However, like ChaosZero above, he too was treated as a troll giving false information, despite having leaked Sonic's exact reveal date. Even the moderators of SmashBoards treated him as such, with Gimpyfish locking the thread and editing his original post to claim he was a liar.
ShadowXOR was another SmashBoards user who was able to test a build of Brawl firsthand that included yet to be revealed characters. He leaked the following:
ShadowXOR was treated like the users above, but his information in particular was treated as absolutely false, since almost everyone believed R.O.B. to be a disconfirmed character after being shown as a Subspace enemy.
On January 18, 2008, a promotional video for Super Smash Bros. Brawl on the official Wii website was posted; this video accidentally leaked hidden characters in the game. Although the video was up for the entire weekend, it was not until Sunday night (Monday in Japan) that a few keen-eyed users noticed something unusual. At one point in the video, a Groudon sticker is highlighted and the faces of Pikachu, Pokémon Trainer, Lucario, and Jigglypuff can be seen in the lower right corner, signifying which characters the sticker can be used to power-up in the Subspace Emissary. At another point in the video, a Claus sticker is highlighted, that showed Ness' head alongside Lucas'. This was essentially confirmation that these characters would be playable (). Additionally, many fans believed that Mewtwo's absence confirmed that it would not be playable, a belief which ultimately came true. Upon realising their mistake, however, the developers took the video down.
David Hayter leaking Jigglypuff
During an October 2007 interview by UltraNeko with David Hayter, the voice actor of Snake, he was asked which Brawl character he would most like to beat up, to which he replied Jigglypuff, inadvertently leaking it being playable in the game. Users on Neoseeker took notice before both UltraNeko's account and TheUltraPhoenix, a channel that archived several of her videos, had went down. An archive of the video remains on user proxyXIII's channel.
Super Smash Bros. for Wii U and Nintendo 3DS leaks
Many fake leaks were spread around during the prerelease of SSB4. The most prominent of these were the Gematsu leaks, which had thousands of followers believing them in their entirety before they were proven partially inaccurate by the inclusion of Robin and Lucina, and disconfirmation of Chrom and eventually Rhythm Heaven's Chorus Kids, as playable characters. Other supposed leaks also proved popular, such as one showing Palutena as a playable character that the creator later admitted was a hoax.
The largest SSB4 leak was the ESRB leak, which, unlike the Gematsu leaks, had very few followers prior to video footage being posted and subsequently taken down by Nintendo due to copyright claims, followed by the official confirmation of Shulk, who was implicated by the leaks. The leak managed to give away a number of playable characters, stages, modes, and trophies, and is one of the largest leaks, if not the largest leak, in Smash history.
In July 2014, a supposed email from Australian classification boards, OFLC, had supposedly indirectly leaked Wario as a playable character due to his use of flatulence contributing towards the game's rating. Wario's playable appearance in the game was later confirmed by the ESRB leak.
Leaks for the post-release of a game became possible with the advent of downloadable content.
Battlefield Ω leak
In the E3 2013 Developer Direct for SSB4, a clip was shown that depicted Mario and Mega Man on the Ω form of Battlefield, despite the Ω forms having not been officially revealed. However, very few people noticed it and the stage was brushed off as the regular Battlefield. The Ω forms were formally unveiled in the April 2014 Super Smash Bros. Nintendo Direct, with the Ω form of Battlefield being identical to what was seen in the Developer Direct.
In early May 2014, a GameFAQs user named jiggensteins posted a topic titled "Two New Characters." in which they claimed that Lucina and Robin would be playable characters. They added that both the male and female versions of Robin would be available and that they would fight using magic.
In July 2014 this information was proven to be accurate with the official reveal of Robin and Lucina.
Prior to E3 2014, a Smashboards user by the name of Ninka Kiwi posted that he knew a friend who was playtesting Super Smash Bros. 4, though he did not divulge any specific information, other than Mario and Charizard having new alternate costumes, with Mario in particular having a new blue costume. Later on in July, Ninka came forward with new information, which included Lucas, Wolf, the Ice Climbers, and Snake being cut, while Shulk, Dr. Mario, Dark Pit, Bowser Jr. in the Koopa Clown Car (with all seven Koopalings as alternate costumes), and the Duck Hunt dog being new characters. While initially disbelieved and seen as too outlandish, a friend of Ninka who gave him the information, named Shun, contacted a Smashboards user by the name of Neo Zero, who revealed to him that he got the information he revealed to Ninka from his own friend, and revealed that his friend recreated and posted two of the new palettes on imgur, before E3 2014. While this was going on, an apparently completely independent source posted a supposedly leaked newcomer list on 4chan (containing Shulk, Chorus Men, Mewtwo, Ridley, Dixie Kong, Duck Hunt Dog, and Bowser Jr.), containing the two characters unique to the, at the time, completely disbelieved Ninka leak. In addition to this, a person in the Smash community known as Vaanrose came forward to Neo Zero that he knew a friend who knew someone who worked at Nintendo of America's offices in Redmond, Washington, who disclosed to him that Robin, Bowser Jr., and the Duck Hunt Dog were playable. With the screenshot proof of prior knowledge of the new palettes, and these new independent sources backing up a completely disbelieved leak, the people involved publicized this additional information legitimizing the leak in a thread on SmashBoards.
The release of Super Smash Bros. for Nintendo 3DS in Japan verified everything described by Ninka and Vaanrose, while the additions made by the 4chan variation of the leak were confirmed false.
Main article: ESRB leak
One of the most notable leaks in Super Smash Bros. history took place shortly before the Japanese release of Super Smash Bros. for Nintendo 3DS. This leak managed to reveal the entire base roster of characters, including Jigglypuff, Ness, Ganondorf, Dr. Mario, Falco, Mr. Game & Watch, Wario, R.O.B., Bowser Jr., Duck Hunt, Dark Pit, and Shulk, none of whom were announced at the time. Although initially considered obviously fake by many, the leak gained momentum and popularity after several gameplay videos featuring Shulk, Bowser Jr., and Ganondorf were released and, shortly thereafter, Shulk was officially announced. YouTube video footage of these characters was shortly taken down by Nintendo of America.
The leak additionally featured several photos of the content sent to ESRB, one notably featuring a trophy of the Fire Emblem character Tharja, which does not appear in the final game. Due to her revealing outfit and her trophy's omission from the game, it is believed that the trophy was cut to maintain a lower content rating.
Ganondorf was accidentally shown prior to his reveal in a video posted by Nintendo on August 29th, in which he can be seen offscreen while Pikachu is taunting. This same video was later re-uploaded on September 1st, edited so Ganondorf could no longer be seen offscreen. The original video is now unlisted.
Ganondorf was mentioned on October 10th by Sakurai in his "Pic of the day" post, discussing the Home-Run Contest. At the end of the post, he remarks, "I wonder if Ganondorf gives you some advantage," despite Ganondorf having not yet been formally revealed.
Ganondorf was officially revealed on October 15th, and is one of the few characters to be leaked multiple times by official material.
Great Cave Offensive leak
On October 5th, 2014, the official Super Smash Bros Facebook page posted a picture recapping the pictures of the day of the past week. Alongside a picture of the Orbital Gate and the 3DS version's title screen, there was also a picture of Kirby and Pikachu riding in a mine cart in a previously unseen stage. The image was captioned as "Kirby's going for a ride in a mine cart. Well, this situation looks familiar. This stage has some rules that are rare in the Smash Bros. series."
The leak was later confirmed as The Great Cave Offensive, and was revealed officially in the Super Smash Bros. for Wii U 50-Fact Extravaganza.
About a month prior to Super Smash Bros. for Wii U's release in North America, online retailer Amazon.com put up a page to allow for consumers to reserve copies of the game. On the product description for the game, however, information was provided that seemed to suggest a variety of new game modes for the Wii U game:
A mode involving Master Hand and Crazy Hand was later revealed by Sakurai in a Miiverse post, and had previously been implicated by unused content found in the 3DS version. The "board game" and "creating stages" modes, however, had never been previously mentioned on Miiverse or other official material, suggesting that unknown information was still available about the game.
The Super Smash Bros. for Wii U 50-Fact Extravaganza confirmed Special Orders as a mode involving challenges made by Master Hand and Crazy Hand, Smash Tour as a board game mode, and a revamped Stage Builder for the Wii U game, verifying everything implicated in the leak.
Roy and Ryu data
Contained in version 1.0.6 of Super Smash Bros. for Nintendo 3DS were new, unused, sound files, seemingly implicated DLC that had yet to be announced. These included, among other things, a victory fanfare "snd_bgm_Z83_F_Roy_3DS" for Roy, which was a duplicate of the existing Fire Emblem victory theme, suggesting he would also return as DLC in the same way Mewtwo and Lucas did, and two files named "snd_bgm_Z81_F_Ryu_3DS" and "snd_bgm_SF01_SF2_Ryu_3DS", both named in reference to Ryu from Capcom's famous Street Fighter series of fighting games; the files contained the victory theme and Ryu's theme, respectively, from Street Fighter II. The discovery of these files was first reported by game modder shinyquagsire23 in a reddit thread posted on April 15th, 2015, and was corroborated later that same day by homebrew developer crediar, who confirmed the files were not present in the game's Wii U version, and the staff of The Cutting Room Floor, a wiki that specializes in unused video game content.
More unused files beyond these were present, among them being the remix used for the Dream Land stage in Super Smash Bros. and Super Smash Bros. Melee and a second Kirby theme, the Forest Stage theme from Kirby Air Ride. The presence of the Dream Land remix and another forest-themed track suggested that the stage would be future DLC as well. A piece of corroborating evidence for this was also found in Classic Mode following the 1.0.6 update, as Kirby characters would sometimes be fought on Battlefield instead of the existing Dream Land stage, with Battlefield presumably being used as an error handler for an expected but not present Kirby stage.
Four days later, following the discovery of these files, shinyquagsire23 reported finding more hidden files in the game. An image of the character data was released; five unused character slots after Mewtwo are named "Mario", presumably as a placeholder for additional DLC characters. Additionally, shinyquagsire23 reported discovering changes to stage data table. The number of inaccessible stage slots had, according to the article, increased from 4 to 14; this includes the slots for Ω forms, meaning there was space for up to 7 more stages and their Ω forms. The discovery of these files suggested there were more stages planned for DLC beyond Dream Land.
Despite the files being present in the update for a long time, it was not until June 13th, 2015 that they were confirmed to represent real DLC content. On that date, Random Talking Bush, an administrator of and contributor to the site The VG Resource, revealed that he had successfully downloaded the 1.0.8 update of the Japanese version of SSB4 from Nintendo's servers before it was set to release; he then proceeded to datamine its contents and post links to them on his twitter account, showing the characters' ending videos, official art, costumes, and trophies, along with the rest of the planned DLC. Later during that day, crediar was able to test out Lucas, Ryu and Roy before their release on his Twitch stream by editing the files to run over Mario.
Parts of the stream were uploaded to YouTube, but have since been taken down by Nintendo of America on copyright claims, similar to how they took videos down after the ESRB leak. All videos on major YouTube channels talking about the leak were also taken down, including those on GameXplain and the late Desmond Daniel Amofah’s Etika World Network.
Roy, Ryu, Dream Land (64), and all other elements implicated as DLC were formally announced and released on June 14th, 2015. Notably, Ryu's victory theme was replaced with a remix as opposed to the direct rip from Street Fighter II present in the 1.0.6 data; also, the Forest Stage track that was found in the 3DS version would end up only being used on Dream Land (64) on the Wii U version, as the 3DS version ended up using Ice Cream Island as its alternate track instead. Furthermore, exactly 7 other stages aside from Dream Land were added to the 3DS version of the game via DLC and updates, including Duck Hunt, which came free after version 1.1.1, and Suzaku Castle, which became available with the same update that Dream Land did.
Super Smash Bros. Ultimate leaks
Several rumors regarding a Smash title for the then-unnamed Nintendo Switch pervaded in the time preceding the announcement of Super Smash Bros. Ultimate, many of them centering on the debate if the system would, assuming a Smash title was going to release, receive a port of an existing title or a completely new one. Following the game's announcement in 2018 and the release of more information in the months that followed, nearly all of them were proven false. Afterwards, however, real leaks began to emerge, ranging from minor ones, such as the premature confirmation by a former employee that Bandai Namco would return to develop the game, to much larger ones, such as the dispersion of an illegal copy of the full game two weeks prior to release, which in itself leaked several details regarding the game.
Main article: Vergeben leaks
On May 16th, 2018, a user known as Vergeben posted a thread on GameFAQs, claiming he had a reliable source with information on the character roster of the then teased but still unrevealed Super Smash Bros. Ultimate. He would later follow up his statements with multiple others later on, most of which had correct information.
At present, the following are the claims made by Vergeben that have been confirmed:
7-11 poster leaks
A notable recurrence during the post-release of Super Smash Bros. Ultimate were posters regarding upcoming and recent Nintendo content being placed up at 7-11 stores in Japan and being taken down at specific dates. These posters, which also detailed information on the Fighters Passes, had many fans correctly guess that the characters would be released before the posters were removed:
Base Game Rumors
Battlefield and E3 2018 Booth leak
On April 24th, 2018, a YouTuber by the name of "Master0fHyrule" claimed on Twitter that a source had told him that Bayonetta, Duck Hunt, and Shulk would return as playable characters for the upcoming game. On the same day, he claimed to have seen the new version of Battlefield and uploaded an image of which he described as "a small piece of it from the Top-Down view".
A day later, a YouTube user by the name of "GU KingofHeart" published a video in which he claimed that he received information about display items being featured at the Super Smash Bros. section of Nintendo's then-upcoming E3 2018 booth. He claimed that his source was the same source that leaked that Nintendo's E3 2017 booth would have a New Donk City-themed area, which turned out to be true. He revealed the following:
These supposed items hinted the return of Bayonetta, Captain Falcon, Fox, Link, Marth, and Shulk as playable characters, the return of the Golden Hammer as an item, and the inclusion of greater Splatoon representation. It also supported Master0fHyrule's claims of Bayonetta and Shulk returning.
In addition to the display items, GU KingofHeart also uploaded an image of what he claimed was the center of the new Battlefield. The image lined up with Master0fHyrule's previous image.
All of the uploaded videos and tweets were deleted soon after they were posted. Discussion of the two leaks mostly remained within ResetEra and SmashBoards. On June 12th, 2018, the day of Nintendo's E3 2018 event, a new trailer for the previously untitled Super Smash Bros. Ultimate was demonstrated. In the trailer, the new Battlefield was revealed and officially confirmed both Master0fHyrule and GU KingofHearts' leaked images as real. The trailer also confirmed that every previous fighter would return, confirming the leaked characters in the process. At Nintendo's booth, all of the display items leaked by GU KingofHearts' source were confirmed to be real.
Rendering engine leak
On May 9th, 2018, a former software engineer and graphics programmer for Bandai Namco named Tiago Sonobe stated on Twitter that after his August 2016 departure from the company, work had begun on a new Super Smash Bros. game using the in-house rendering engine which Sonobe had developed. Following the spread of the tweet, Sonobe's Twitter account was entirely deleted.
E3 2018 4chan leak
As with many Brawl leaks, the leaker was considered a troll and mocked for their claims. During the Direct, his information was confirmed mainly factual.
The leak made a few notable errors, such as claiming that Lucas was an Echo Fighter, that Inkling's Final Smash would be a Squid Sisters concert which would cause the screen to zoom in, and that all stages would have a Final Destination and Ω form (which are the same thing). In reality, Lucas is treated as a fully separate character from Ness, the Squid Sisters were revealed to be an Assist Trophy with the same function while Inkling's Final Smash was confirmed to be Killer Wail, and it was confirmed that stages would have both a Ω form and a Battlefield form. However, given that the rest of the information was correct, as well as the fact that the same user correctly predicted the title and gameplay style of Super Mario Party, another game featured in E3 2018, it is likely these errors were made from misinterpretation or assumption rather than being evidence of a false leak.
Loz18 E3 2018 leak
On June 11th, 2018, GameFAQs user Loz18 made a thread about Ultimate before its E3 reveal. In the first post, he stated the following:
Two days after the E3 reveal, he made another claim about an August Nintendo Direct. Although a Super Smash Bros.-themed Nintendo Direct was confirmed for August 8th, the rest of his information was proven inaccurate to various degrees.
Castlevania music leak
The night of August 7th, 2018, close to the airing of the Super Smash Bros. Ultimate-centered Nintendo Direct the following morning, the YouTube video for the Galaga Medley on Nintendo's Super Smash Bros. channel that was previously confirmed the week prior was renamed to "Bloody Tears / Monster Dance", both of which are tracks from Castlevania II: Simon's Quest. It was later properly renamed back to "Galaga Medley".
Following the Direct, which announced Simon and Richter as new playable characters from the Castlevania series, "Bloody Tears / Monster Dance" was properly uploaded to the website. Due to this incident, all the music previews were renamed to numbers, with each new upload incrementing by one.
Spirits mode leak
Shortly after the August 2018 Smash Direct, Twitter user NoctuleScent made a twitter thread documenting his attempt at deciphering the name of an unannounced mode, shown in the Direct as part of Ultimate's menu, hidden behind a pixelated blur filter and to be revealed at a later date. The tweet claimed that the mode's name was "Spirits", discovered thanks to a "mistake from the editing team", in which parts of the name can be seen for 2 frames as the menu zooms away from deselecting Smash mode. Another tweet shows the name with both frames juxtaposed with image editing software for better clarity. This was corroborated by another Twitter user, Joe Pines.
Shortly after the original tweet, another one from the original user explained that the same method can be used for the Japanese version of the Direct, revealing a direct translation of "Spirits" in katakana (スピリッツ, Spirits). Another tweet claimed that the logo above the name resembles a magatama, an item often associated with spirits, further drawing a connection to the name.
In the Super Smash Bros. Direct on November 1st, 2018, the formerly unknown mode was revealed as "Spirits", confirming the leak.
CoroCoro stages leak
The September 2018 issue of CoroCoro, a Japanese magazine, featured information about Ultimate: though most of it was a retread of what had been in the August 2018 Smash Direct, the magazine stated that the game would have 108 total stages. This was contrary to the aforementioned Direct, which instead stated that the game would feature 103 stages. While this could be assumed as a printing error, many users noticed how this number perfectly matched with the stage selection screen shown in the Direct, with room for six more spots.
The October issue of CoroCoro dropped the stage count back to 103. It is unknown if the September issue's count was a misprint or something that they were not allowed to reveal, although it should be noted that 5 stages were released as DLC for the first Fighters Pass, bringing the stage count to 108.
No new Codec Conversations
On September 8th, 2018 in Fan Expo Boston 2018, a fan asked David Hayter (the English voice actor for Snake) about Ultimate, and Hayter replied that more Codec Conversations hadn't been recorded yet. This led some fans to believe that the Codec Conversations would not be in the game at all. Some that played the demo cited the removal of the Star Fox Smash Taunt in Lylat Cruise, though others guessed that it simply was disabled for the demo. As Pit's Star KO voice clip was completely new, some believed that both Palutena's Guidance and the Codecs could have been rerecorded. Others noted that Hayter was likely bound to a non-disclosure agreement and thus was forbidden from discussing anything not permitted by his contract; however, Hayter himself brought up the topic of Codec Conversations without being asked specifically about it, even after openly acknowledging that he probably was not supposed to say anything, which makes it unlikely that he was trying to obfuscate the truth. Hayter also expressed dismay on not being able to record new lines for Ultimate codecs. Additionally, Takeshi Aono, Roy Campbell's Japanese voice actor, passed away in 2012, and future Metal Gear titles do not feature the character out of respect for Aono. This made it more likely that no new Codec Conversations would be recorded.
It was later revealed from early copies of Ultimate that the Codec Conversations from Brawl return, but that there are no unique Codec Conversations for characters (re-)introduced in Smash 4 or Ultimate. This is in line with Hayter's previous statements that he had not recorded any new voice lines for the game. However, Palutena's Guidance did receive new voice lines in Ultimate for veterans not in Smash 4, Piranha Plant, and redesigned characters.
On September 14th, 2018, Reddit user Noatesty made several posts where they claimed to be a playtester for Ultimate and shared several details about then unrevealed content.
In their first post, Noatesty claimed that Ken and Incineroar would be the final playable characters in the base game, and that Flies & Hand from Mario Paint would be an Assist Trophy. They also shortly described Spirits, comparing them to Brawl's stickers, detailed Fishing Rod's functionality as a tether recovery, and claimed that the game would receive a day one patch with new modes, and that the internal codename of the game was "Cross2".
In their second post, Noatesty further described Isabelle's moveset, claiming that her forward, back, up and down aerials, which had not been shown at the time, were similar, if not identical, to their respective counterparts in Villager's moveset.
In their third and final post, Noatesty claimed that a Piranha Plant was going to be the first downloadable character, and said that it did not have its iconic fireball attack anywhere in its moveset. According to them, it was only accessible via a debug menu in the test build they played. They also described Incineroar's moveset, claiming that it would mostly consist of wrestling moves; its side special appeared to not be based on any existing Pokémon move, but instead had it summon ropes and launch opponents against them. It also had a purple alternate costume that they claimed resembled Sonic character Big the Cat.
On November 1st, 2018, Ken, Incineroar and Piranha Plant were revealed as playable characters, the lattermost as DLC, while Flies & Hand was revealed as an Assist Trophy; it would also reveal that the mysterious mode teased in the previous direct was called Spirits and featured collectibles similar to stickers. Later that day, the Nintendo Treehouse stream also validated Noatesty's claims about Isabelle's and Incineroar's movesets. On November 28th, 2018, it was announced that the game would receive a day one update, although the contents of the update were not disclosed in detail. After the update was released, it was revealed that downloading it would enable online modes and add a Hard difficulty setting to World of Light; it is unclear if these are the modes that Noatesty was referring to. Datamining the game also revealed that the internal project name was indeed "Cross2".
On September 21st, 2018, an anonymous 4chan user posted a cropped screenshot of Ken Masters from the Street Fighter series on Moray Towers. Later, the user uploaded the full screenshot to the same thread, showing off Pichu, Ivysaur, and Pac-Man taunting alongside Ken on the Moray Towers stage. Allegedly, Ken's model is not a port of another game, but a new model altogether.
Some users pointed out that the portrait of Pichu had its ear cut off, which actually matched up with the E3 reveal trailer. Ken was partially standing on a metal surface where his shadow does not appear under his foot: SmashBoards user DJ3DS recreated the shot in the demo build with Pikachu and Ryu instead of Pichu and Ken; the shadow is missing from the metal surface in the demo build, meaning that the error in the leak does in fact exist in the game.
Ken was announced on the November 1st Super Smash Bros. Ultimate Direct, with his model and render matching with the one in the photo.
Piranha Plant 4chan leak
On September 24th, 2018, an anonymous 4chan user made a thread claiming that the final three newcomers in Ultimate would be Incineroar, Ken (as an Echo Fighter based on Ryu), and Piranha Plant. They also elaborated on Piranha Plant's playstyle, saying that it would be in a vehicle of some sort in a similar vein to Bowser Jr.
On November 1st, 2018, Incineroar, Ken, and Piranha Plant were confirmed to be playable fighters in the final pre-launch Super Smash Bros. Ultimate Direct. However, while the 4chan user's assertion that Ken would be a Ryu Echo Fighter was correct, their claim that Piranha Plant used a vehicle was proven to be inaccurate, with it instead being in a pot or Warp Pipe (depending on the costume selected) and walking on its roots which extend from the bottom of its vessel, though this was more likely a misconception than deliberately false information.
Healing Sprout leak
On October 26th, 2018, Nintendo of America uploaded a video onto Twitter showcasing and promoting their Wendy's College Tailgate Tour, with several clips of full gameplay intertwined with demo gameplay. For a split second, on Mute City, a circular unrevealed item with a stem and two leaves could be seen; fans quickly took notice that this item bore a strong resemblance to the Growth Psynergy from Golden Sun: Dark Dawn.
The item was revealed to be Healing Sprout on November 1st, 2018, a new item unrelated to Growth Psynergy. However, Isaac was confirmed on the same day to return as an Assist Trophy, meaning that Golden Sun representation returned nonetheless.
Completed Game leak
Two weeks prior to the release of Ultimate, a leaked copy of the game was distributed across the internet, in part due to an accidental release in Mexico. Nintendo took steps to issue copyright strikes on YouTube videos using data mined content, while fans worked to isolate spoilers, particularly the World of Light story mode, from those that had played the leaked version. As the entire roster and selection of stages were all revealed before the leaks, very little info shown off from those were not already known. However, the following information that was previously unknown was shown off:
Fighters Pass Vol. 1 Leaks
On October 11th, 2018, Twitter user Milk-BOSATU (currently named Team NepDon) made a tweet that claimed that the Hero from Dragon Quest series is a playable character with no female alternate costumes alongside with VR content for the Switch coming. VR content for the Switch was later revealed as Nintendo Labo VR Kit March 2019 and the Hero was later confirmed to be a DLC fighter in the Fighters Pass Vol. 1 at E3 2019.
On November 28th 2018, a technical data Discord server uncovered Ultimate's character parameters table (the list of values such as walk speed and weight) and began decoding it in preparation for the game's release (Ultimate uses hash functions to store strings, so they are not immediately evident and require knowledge and patience to crack). It was found that the first column in the table stored each character's internal development name. It quickly followed that, not only were Piranha Plant's values already included in the table under "packun" (its Japanese name being Packun Flower), but there was one further slot named "jack". After the 1.1.0 update was made available on December 5th, a second unknown character's attributes were found to have been added, called "brave". Out of respect for players and the game's development team, these discoveries were kept secret.
On January 3rd 2019, the existence of "jack" and "brave" began to quickly spread from an unknown source. With Joker having been revealed, it was assumed that he was "jack" (as "jack" and "joker" are both types of playing cards). "Brave", however, was less clear. The most common speculation was a Hero from Dragon Quest; the default class in most games of the series is 勇者 (Yūsha), which means "Hero" and directly translates to "brave" in English. The parameters of "brave" revealed that their weight is between Mega Man and Cloud/Mii Swordfighter, their running speed is between Young Link and Kirby, and they did not have a neutral infinite, wall jump, or crawl. As confirmed upon his release, this data does indeed refer to Hero.
Later, text strings were discovered in the game data that seemingly referred to upcoming DLC. Due to a technical oversight in a particular file format used for Ultimate's stage data, unrelated development text leaked into stage data files. The string "Jack_Menentoes_" was discovered, confirming Joker's stage as Mementos from Persona 5. Another discovery seemed to imply that one or more of Joker's alternate costumes was an alternate character who has a ponytail hairstyle. However, Joker released with no such costume, implying that the data was scrapped during development.
Extra game modes datamine
On March 8, 2019, Ultimate's files were datamined, revealing two files named "howtoplay_stage_builder.html" and "howtoplay_homerun.html". The intended purpose of these files is unknown, but it has led fans to speculate that Stage Builder and Home-Run Contest are returning to Ultimate in a future update, with "howtoplay" signifying that the files are for a menu that pops up when the player first selects the modes.
A leak in an advert by Nintendo would later reveal that a Stage Builder was in fact being developed, and it was officially revealed on April 16, set to be released the following day. Home-Run Contest would later be confirmed and released on September 4th with the version 5.0.0 update.
Joker Render leak
On March 31, 2019, Best Buy published a weekly ad about the Fighters Pass Vol. 1 featuring a render of Joker, creating speculation that Joker's release date and/or gameplay reveal would be at or around the first week of April.
On April 1, 2019, the page was edited to replace the ad for Ultimate with a fast store pickup ad, thus removing Joker's render alongside it. This spread further speculation that it was his still unrevealed official artwork for the game.
2 weeks later on April 16, Nintendo of Europe's databases added the image of the full render of Joker. That same date, Nintendo released information through a video that Joker would be released the following day, April 17, and fully confirmed the legitimacy of Joker's render.
Stage Builder leak
On April 9th, 2019, Nintendo uploaded an ad related to Ultimate; fans quickly noticed that a mere one second in, a "Stage Builder" option could be seen under "Games and More" on the menu. This seemed to imply that one of the new modes to be added in the 3.0.0 update was going to be a Stage Builder mode, seen previously in Brawl and Smash 4, but notably absent in Ultimate. This was further supported by the Nintendo Direct aired on February 13th, 2019, which showcased a blurred out image of what was believed to be Stage Builder. Due to the video not being covered up or deleted like the one that revealed Ganondorf, some have speculated that this was in fact not a leak but an intentional marketing ploy.
Stage Builder would later be officially confirmed in a special presentation video about version 3.0.0 on April 16, 2019.
Banjo & Kazooie leak
On June 4th, 2019, ResetEra admin shinobi602 made a post a week before E3 2019, stating: 'Been a while since we saw Banjo in anything. Hope we’re in for a smashing good time.' The phrase "have a smashing good time" is notable in that ResetEra admins had used the phrase to tease upcoming Super Smash Bros. content in the past. ResetEra has strict policies about users posting rumors, and as shinobi602 was an admin, along with his perfect track record regarding leaks, this lead many people to believe that shinobi602 was teasing an upcoming Banjo-Kazooie reveal at the E3 2019 Nintendo Direct. This leak was eventually supported when Banjo & Kazooie were revealed as a part of the Fighter's Pass for Super Smash Bros. Ultimate at the E3 2019 Nintendo Direct on June 11th, 2019.
Hero July release date leak
On July 16th, 2019, Nintendo uploaded a video under the name "Fan-Favorites & Newest Releases - July" which showed brief clips of Marvel Ultimate Alliance 3: The Black Order and Fire Emblem: Three Houses, two upcoming games slated to launch in July, as well as Fortnite, the ninth season of which was currently ongoing, and Hero in Super Smash Bros. Ultimate. This led many to believe that Hero would launch sometime in July. Nintendo later renamed the video to "Fan-Favorites & Newest Releases - Summer".
On July 30th, Hero was confirmed to release on that day.
Dragon Quest spirit board leak
Sometime later, Nintendo took down the images. All of the spirits were later confirmed to be in the game, as a part of the Dragon Quest DLC Spirit Board.
Nintendo of Europe 4.0.0 release date leak
On July 29th, 2019, Nintendo of Europe posted a Tweet containing a release date for the then-upcoming 4.0.0 update, being July 31st. The Tweet was then taken down, and replaced with a Tweet which instead stated "within 7 days".
The following day, Hero was confirmed to release on July 30th in North America (July 31st in Europe due to time zones), the day the presentation for Hero aired.
Nintendo of Europe site SNK fighter leak
On September 1st, 2019, a page for the 4th challenger pack in the Fighters Pass was created on Nintendo of Europe's website. Within the page was the mention of a copyright belonging to SNK Corporation was found. It was speculated to be borrowed from the DLC pages for SNK Heroines: Tag Team Frenzy due to having an identical filesize and an incorrect date. However, after cross-checking with the other fighter pack listings and Nintendo pulling down the page soon after its posting, the SNK copyright was confirmed to be a legitimate mistake. Three days later, Terry from Fatal Fury would be confirmed as the SNK character for the Fighters Pass.
Spirit Board Event SNK Copyright
On October 30th, 2019, the notification for the Spirit Board Event Smash by the Sword went live. The event ran between November 1st to 4th. Located at the bottom of the notification is the copyright for the SNK Corporation, which was newly added. This led to rumors that Terry's release date would be near the beginning of November. This speculation was eventually proven correct with Terry's release on November 6th.