The new smash bros. game will use the gamecube controller instead. The controls are the same as smash bros. melee
Nintendo is pushing this game as a tournament fighting game, since melee has been a huge tournament fighting game around the world. The creators of the new one wanted to keep the same control scheme
Obviously, there will be new moves, and alot more characters. Rumored characters not announced are: Pikmin, Diddy Kong, Nintendogs (yes that is what I said), and the twilight princess.
These are all rumors, so we will see, but there will be alot of new characters.