In the first SSB, he has the ability to float around, and all his moves are "activate and wait for it to happen". He wouldn't work outside of a mode due to having HP differences.
But he is very easy to play and works fine.
In Melee, as mentioned earlier, he's far worse. You can't make him move anywhere, and need to use the D-Pad directions and Buttons to make him move, which is instead of regular "movement", he just does a mapped "Move"(as in an attack).
In the first game, to clarify, he has the same controls as every other character, except he doesn't have a move for every possible combination.(like might not have Smash Down A, for instance) He also has a Forward B, which is the first time it was used, not Melee(fun trivia, yeah). He only works correctly in Final Stage(named Final Destination in the second and third game).
I don't believe anybody has played as him in Brawl yet, so the movelist is unknown.