During the most recent Nintendo Direct, it was revealed that Super Smash Bros. for Wii U can be operated by a grand total of six various peripherals — and that includes the 3DS! The classic GameCube controller will also be available for usage, as well as the Wii U Pro Controller, the Wii Remote Plus (and nunchuck, if you want), the GamePad, as well as the Wii Classic Controller.
Which one will you use?
Source: Super Smash Bros. Direct