I beat him normal at lvl 53 (I think)
Sephiroth was the most difficult for me. Kurt didn't give me any trouble, but I didn't even attempt any of the special bosses til lvl 70
I'm not an expert, but Tinker Bell help as well as hiding in the tree like things and letting donald and goofy do the work until they pass out
Uh... People can do that kinda stuff, but I find stuff like that somewhat disturbing...