Go on training mode and slowly get used to how everything works on the GC controller: do shorthops, fullhops, weave in an out of platforms, repeatedly do all of your moves, get used to doing aerials with
, and if you feel uncomfortable with something, now is the time to switch up your controls, and maybe you could consider picking up the
Bidou control scheme before getting used to anything else. If you have friends (preferably ones that have patience to tolerate you flubbing basic stuff at first), play against them, and force yourself to use the new features the GC controller grants you as much as you can. If you really don't have any friends available, practice with bots, but don't go overboard. Only practice enough for you to feel comfortable with it.