Dr. Mario's -> A smash attack is different too
Luigi has a different -> B attack, plus has A LOT more hangtime and less traction
and, the problem with adding more characters is that you have to balance them out with EVERYONE else so that any character can kill any character
BTW: play against a lvl 9 ness (set to 2nd player position) on Jungle Japes and he commits suicide EVERY time. if im wrong set ness to 3rd or 4th. but it HAS to be lvl 9