I tried to do this, it's not quite as simple (same goes with running speed).

Disabling stomping, uppercut, buttstomp, copter, sidekick and double jump are actually just a matter of changing a few variables from their normal values. Sometimes it requires exploiting a bug, other times it's just stuff like tricking the game into thinking you aren't jumping even when you are. Actually adding new moves is a lot harder (though not impossible). The only one that would be quite easy is something like an infinite double jump, or something like that.