Super Smash Bros. for Nintendo 3DS / Wii U

Super Smash Bros. for Nintendo 3DS / Wii U (tentative title) is the upcoming fourth installment of the Super Smash Bros. series being developed for both the Nintendo 3DS and Wii U. Like previous games in the series, it is being developed by Sora Ltd. and directed by Sora Ltd. founder Masahiro Sakurai. On June 2012, it was announced that Sora Ltd. is working alongside Namco Bandai Games in developing the game. In the Nintendo Direct of E3 2013, Mega Man from the Mega Man series by Capcom was announced as the third guest character of the series, after Snake and Sonic from Super Smash Bros. Brawl.

Gameplay
Not much is known between the two versions currently. Final Smashes return from the previous installment in the series, Super Smash Bros. Brawl.

3DS version
The 3DS version has cell-shaded style graphics along with stages based mainly around handheld titles. Characters have been given outlines too make seeing them easier.

Wii U version
The Wii U version has HD graphics along with stages mostly from console games.

Returning characters

 * Mario - Mario has been given brighter blue overalls with less detail compared to the overalls in Super Smash Bros. Brawl.
 * Donkey Kong - Donkey Kong's fur looks slightly more detailed compared with his appearance in Brawl.
 * Link - Link's skirt has more prominent frills.
 * Samus - Samus' appearance has been updated to reflect her appearance in Metroid: Other M.
 * Kirby
 * Fox - Fox's fur looks much more detailed than in his appearance in Brawl.
 * Pikachu - Pikachu appears to be slimmer than in the past installments.
 * Bowser - Bowser has a more upright stance and his running speed and attacks are faster.
 * Pit - Pit's appearance and moveset have been updated to reflect his appearance in Kid Icarus: Uprising.

Newcomers

 * Villager
 * Mega Man
 * Wii Fit Trainer

Others

 * (Mega Man 1)

Stages
According to Masahiro Sakurai, the 3DS version of the game is going to feature more stages based on games for Nintendo handhelds, while the Wii U version is to feature more stages based on console titles.

Nintendo 3DS

 * A stage appearing similar to Battlefield from Super Smash Bros. Brawl.
 * Gerudo Valley, from The Legend of Zelda: Ocarina of Time.
 * A stage taking place on the Spirit Train, based on The Legend of Zelda: Spirit Tracks.
 * Arena Ferox, from Fire Emblem: Awakening.
 * A stage taking place over a water area with spiked pillars that rise onto the stage, based on Super Mario 3D Land.
 * A stage based on Nintendogs, taking place in a giant room with a dog playing in the background.
 * A stage which resembles World 1-1 from New Super Mario Bros. 2.
 * A stage taking place in Super Mario 3D Land.
 * A stage based on Kid Icarus: Uprising.
 * A stage based on Donkey Kong Country Returns 3D.

Wii U

 * A stage similar to Battlefield in Super Smash Bros. Brawl.
 * Skyloft, from The Legend of Zelda: Skyward Sword. (Much like the Delfino Plaza stage from the previous game, platforms will rise every few minutes to change to a different location in Skyloft)
 * A wrestling arena-type stage.
 * A town, based on the Animal Crossing series.
 * Dr. Wily's fortress from the Mega Man series; The fortress itself is based on the design seen in Mega Man 2.
 * A stage based on Wii Fit.

Items

 * Capsule
 * Smash Ball
 * Wii Fit Soccer Ball