Shin Shoryuken / Shinku Hadoken

Ryu's Final Smash is unique in that it is the first Final Smash with two distinct variants: Shin Shoryuken (, True Rising Dragon Fist), a three-hit trapping combo, and Shinku Hadoken (, Vacuum Surge Fist), a projectile. Which attack he uses depends on how close he is to an opponent.

Shin Shoryuken
If Ryu uses his Final Smash right next to an opponent, he will perform the Shin Shoryuken (, True Rising Dragon Fist), a powerful 3-hit version of his up special, Shoryuken. It has extremely high KO power, but requires precise positioning and typically focuses on a single target.

Upon use, the camera zooms in, and Ryu stuns the opponent with a flash of purple lightning that cuts across the screen (dealing 1% damage), before swinging his right fist for an uppercut (10%). He then performs another uppercut with his left fist, briefly pausing mid-uppercut against the opponent's chin while grunting the word "Shin..." (10%), before leaping upward and announcing "SHORYUKEN!!" (20%). The first two punches cause white ink-like effects, while the final blow causes black ink to surround the opponent while violent action lines focus on the Final Smash's victim.

The move deals 41% damage in total, and the final hit is extremely powerful, enough to KO reliably at 28%, although Ryu has to be close (sometimes even touching) the opponent for it to activate, otherwise his Final Smash becomes the Shinku Hadoken. The Final Smash can miss at this range as well, either due to intangibility, or being too far away to be trapped; if so, Ryu performs a 6-hit Shoryuken, dealing only 15% damage, before landing on the ground. This version originates from  as a failsafe in case the regular Shin Shoryuken misses. This move has since been officially titled Forbidden Shoryuken (, Forbidden Hand Rising Dragon Fist) and has reappeared in several Street Fighter games, even becoming a standard special move for Ryu's teacher, Gouken.

There is a unique aesthetic effect of the final blow if the opponent is dealt enough knockback to be KOed: the entire screen becomes covered in an orange background, along with a unique sound effect and Ryu announcing "SHORYUKEN!" in a fiercer tone. This background and sound effect are used in the Street Fighter series when a fighter is KO'd by a Super or Ultra Combo. The background does not appear if the last hit does not have enough force to KO the opponent (e.g. if the opponent is at 0%).

In Ultimate, characters have unique hitstun animations for being hit by this move.

Shinku Hadoken
When there are no opponents directly in front of Ryu, he will perform the Shinku Hadoken (, Vacuum Surge Fist), a powerful version of his neutral special, Hadoken.

Upon use, the camera zooms in on Ryu while he gathers great amounts of blue energy (Ki) into his hands. He then announces "Shinku... HADOKEN!!", before firing a large blue projectile. Despite the projectile's small size (being only somewhat bigger than an Input Hadoken), it has a strong vacuum effect, which pulls opponents towards it and makes the move deceptively difficult to escape from. Opponents trapped in the projectile take constant damage, and are sent flying when the projectile explodes after traveling the distance of Final Destination.

Shinku Hadoken deals a maximum of 29-30% damage (19 repeated hits for 19%, final hit dealing 10% and carrying all the knockback), assuming the opponent is trapped the moment Ryu unleashes the projectile. The final hit's knockback is somewhat lacking for a Final Smash, only KOing at 115%; it is therefore more efficient to take advantage of the projectile's vacuum effect to drag opponents towards the blast lines, where it can KO much earlier. Finally, the attack overall has little end-lag compared to most Final Smashes, allowing Ryu to quickly get into position to finish opponents who survived the attack.

Canceling
Thanks to his special move canceling mechanic, Ryu can cancel many of his moves into Shin Shoryuken. By pressing the special button after connecting with one of his standard attacks or most special moves (i.e. all except Focus Attack) Ryu will cancel the endlag of an attack straight into a Shin Shoryuken. It is impossible to cancel attacks into Shinku Hadoken, as it can only be activated when opponents are outside of attack range.

Shinku Hadoken
The Shinku Hadoken first appeared in ' as his trademark Super Combo (its name wasn't originally presented onscreen until ') that later appeared in several games ever since its debut. In most Street Fighter games, it is a somewhat-larger, a multi-hitting version of the Hadoken which paved way for projectile durability ratings in other fighting games (when different projectiles clash with each other to see which one comes out on top).

In most of the Vs. Capcom crossovers, it instead becomes more akin to a laser beam akin to the Kamehameha technique from the  franchise. In-universe, it is a Hadoken coated with vacuum energy to increase its damage and size, hence the literal translation of the technique's kanji. In those games, Ryu is able to perform both his normal Hadoken and Shinku Hadoken in the air.

Shin Shoryuken
The Shin Shoryuken was introduced in  as Ryu's second Super Art, which also appeared in several games since its debut. As such, the Street Fighter III series version of his final smash is the one the Smash version is based off of. This move was first taught by his master Gouken. The version seen in Smash combines the effects of both the first two hits of Gouken's Shin Shoryuken with the final hit effect of Ryu's Metsu Shoryuken. In some games, Ryu would perform a spiraling turn true to Shoryuken-fashion at the peak of his rise (in most old Vs. Capcom series games), while in the attack's standalone debut in Street Fighter III and in recent titles he and Gouken omit the classic peak-turning motion.

In Street Fighter Alpha 3 (or Zero 3 in Japan), Ryu would be able to perform the Shin Shoryuken out of his Metsu Shoryuken Super Combo only if he hits with the very final frame of his initial elbow lunge (practically out in the open, it requires very proper and specific spacing). Otherwise, Ryu will perform a normal Shoryuken as the finisher.

The screen that shows up in the background on the final strike of Shin Shoryuken is the KO screen from the  games, which would show up whenever the opponent lost all their health at the end of a round if attacked by a Super/Ultra Combo.

Finally, the fact that Ryu has two Final Smashes is a reference to the Ultra Combo Double mechanic introduced in  where the player, instead of sticking with one Ultra Combo or the other, can use both at the cost of reduced damage on each one. In Ryu's case this would be the Metsu Hadouken and the Metsu Shoryuken.

It may also be a reference to how in Street Fighter IV, some Ultra Combos would change if they missed or were blocked. Some examples are Ken's Shinryuken becoming a simple flaming uppercut if it misses (making it akin to the original Shinryuken prior to Street Fighter IV) or Oni's Tenchi Sokaigen being a shockwave instead of a cinematic uppercut should the opponent block it. Ryu's Shin Shoryuken in the Street Fighter III series, Marvel vs. Capcom 3, and his Metsu Shoryuken in Street Fighter IV all also share this property, becoming simply stronger and/or multi-hit Shoryukens if they miss or are blocked (as well as being spaced properly so the initial Shoryuken connects in a way to not trigger the actual attack). Ryu's Shin Shoryuken in Super Smash Bros. retains this as well.

Trivia

 * Using the "Fixed" camera in Training Mode shows that Shin Shoryuken's "KO" background covers the entire stage, while the "action lines" that appear around Ryu and his victim end in a circle surrounding them.
 * This is the first Final Smash in the Smash Bros. series that completely changes depending on range. This hence makes Ryu the first fighter to technically have two Final Smashes in the same game, with the second appropriately being Ken.
 * Additionally, as Ryu can perform his neutral special move, Hadoken, with directional inputs and both the standard and special attack button, he is the only fighter who can use his neutral special move while having a Smash Ball's glow, not counting glitches or when the Final Smash is not fully loaded.
 * Shin Shoryuken uses the same animation that Ryu's sprite uses in the Street Fighter III series.
 * The black ink surrounding the opponent during the Shin Shoryuken is a Street Fighter IV aesthetic; however, Ryu can not use the move in any Street Fighter IV game.
 * In those games, he instead uses a more powerful version called the Metsu Shoryuken, while the Shin Shoryuken is used by another character, Gouken.
 * Shin Shoryuken is one of only two Final Smashes to leave the user helpless, the other being Rocketbarrel Barrage in Brawl.
 * This is somewhat faithful to the Street Fighter series, wherein a missed or blocked Super or Ultra Combo will usually leave the user open to a counterattack.
 * Ryu uses the opposite fist he would use for a regular Shoryuken for Shin Shoryuken.
 * However, a missed Shin Shoryuken uses the same fist as the regular Shoryuken.
 * A missed Shin Shoryuken also has a grinding effect when colliding with another foe, similar to Sakura's Shouoken from the Street Fighter Alpha series.
 * Despite being named after both moves and describing them as well, Ryu's Final Smash Trophy only depicts Shin Shoryuken.
 * The Shinku Hadoken having a vacuum effect (something it has never displayed in other appearances) may be a joke on its translated name - "Vacuum Surge Fist" (despite it referring to the vacuum of space).
 * In the game version of Ryu's initial release, 1.0.8, if an opponent somehow escaped the Shin Shoryuken, the game would crash. This was fixed in a later update.
 * The inputted version of Ryu's standard Shoryuken is often referred to as the "True Shoryuken", which is, funnily enough, the translated name of the Shin Shoryuken ( meaning "true").
 * If the player listens closely, they will hear the same sound effect that plays right after performs a successful KO Uppercut right after an opponent gets hit with the final hit of Shin Shoryuken. Prior to Super Smash Bros. Ultimate, it was the only other move to use this sound effect.