Super Smash Bros. 4
An untitled fourth game in the Super Smash Bros. series, currently referred to as Super Smash Bros. 4 or SSB4, is currently in early-stage development for the Wii U and Nintendo 3DS by Namco Bandai and Sora Ltd.
When originally announced in passing at E3 2011, the game's development was slated to begin sometime after October 2011, once development on Kid Icarus: Uprising had completed.  In February 2012, it was then confirmed that development on the fourth game had begun. The game was unmentioned during E3 2012, something which many fans were disappointed about despite the known extremely early state of the game; the "first step of the process" was taken shortly after in mid-June. Sakurai has expressed disappointment that fans will be waiting for longer than expected for the game to be released due to the earliness of the initial announcement. Shortly afterward, it was revealed during a Nintendo Direct that Namco Bandai was the primary developer alongside Sora Ltd., and had already completed a working prototype.
Sakurai has stated, in response to a fan asking him about whether a "child Link" would appear in the game, that he has not currently decided on who would appear in the game. However, he has also said that he "can't say that it's entirely out of the realm of possibility that some Capcom character could appear in the next Smash Bros."
Sakurai has revealed that one feature of the 3DS Smash Bros. title will be that players can improve their character through battles and rewards, then transfer them to the Wii U Smash title to play against friends. He said the 3DS title is intended to offer a new experience for veteran Smash Bros. fans, and that neither the 3DS game nor the Wii U game would simply be sequels like Melee and Brawl were, and that they'd do more than just add characters and stages. It has also been revealed that they are looking towards co-operative play for the Wii U title. Official Nintendo Magazine said "there is merit in having skilled and unskilled players play together, so one emphasis will be on elements of players helping one-another". They also stated that the graphics would be significantly stepped up, as the Wii U can handle high quality graphics, dynamic effects and smooth character movements in HD at 60 frames per second. Sakurai is also quoted as claiming that the new game is unlikely to emphasize new playable characters, focusing instead on gameplay balance and distinctiveness of its characters. 
On July 2nd, 2012, Sakurai posted a whiteboard drawing on Twitter which was drawn by the game's staff. It depicts a Pikmin, Marth, Kirby, Meta Knight, Luigi, Pit, Pikachu, Link, Wario, Sandbag, a Heart Container, Mr. Game & Watch, Fox, Donkey Kong, a Mr. Saturn, Mario, and Zero Suit Samus. While it came with no explicit confirmation of any of these characters or elements as reappearing, it does show they are in some sense acknowledged by the staff working on the game. The sketch also has what appears to be large block letters hidden below the visible area.
Many rumors have spread concerning the game, but none have been confirmed. A notable one claimed that the game would be called "Super Smash Bros. Universe" and have 3DS and Wii U connection. The rumor also said that there would be no new EarthBound or F-Zero characters. It was revealed that this rumor had come from a official source, but only to recruit people towards the game's development. There has been no further mention of this name, nor have any characters been confirmed.