(Ok i havent tried this yet) First you must have completed the game in any mode(easy,medium,hard) Then go to a world that has at least 1 heartless(I recommend the land of dragons) once your in a battle with heartlesses, make sure that donald and goofy doesn't kill them then go to wisdom form.Once done make sure that the heartless attacks you (but you dont attack them) until your drive gauge finishes. Then attack them until you get your drive gauge back.and find another group of heartless and turn into wisdom form again and wala!you got a heartless form.