Okay, let's get something straight here real quick:
Sora and Riku go into the sleeping realm or whatever, and are unable to protect the real worlds. And somehow Maleficent and Pete know about this. They also somehow knew that nobody strong was at Disney castle. However, they did not act on this very well.
What do they do? The two kidnap a completely unguarded Minnie, in an unguarded Disney castle (well not totally unguarded, but all that were there were just KH's version of red coats), and just wait there for Mickey, Donald, and Goofy to come back......What the heck?
Okay, please correct me if I'm wrong, but doesn't Maleficent have some control over the Heartless? And Pete too, through her. So why didn't they bring a whole army of Heartless, or at least a few really big ones, and lay siege to the castle? And technically Maleficent has like a whole army of little goblin thingies, but I don't think they ever showed up in the games.
And for that matter, where were all of the other Disney villains? Surely Maleficent still had ties with them. Yeah Ursula showed her ugly face up but failed miserably.
I mean really, this is just so stupid. They just wanted this game to be all about dumb ol' Xehnahort (again), and only him (again) that they forgot a big chunk of the Disney aspect of this. I mean the Disney villains are not stupid, or weak, give them some credit.
And on a slightly different note, what's stopping all the Disney villains from trying to get the Princesses of Heart again? If they know Sora and Riku cannot get in their way, then they should know it would be pretty easy to capture the Princesses.