^ wisdom, the best place is in TWTNW
the alley to between? go to that save point, and go to the streets from there, if you turn, you will see nothing but shadow heartless that keep respawning, just turn into wisdom and shoot their butts off (remember it doesn't matter whether you kill a fat bandit or a shadow, everytime you kill a heartless you get 1 exp.)
when your gauge is almost out, run to the save point and get on the gummi ship, and then come back to TWTNW. your gauge will be completely filled again. Keep doing it until you hit level 7 ^_^
Final form's best place to level up is the mysterious tower, go to the save point in the tower entryway, and walk out side into the green grass and turn into final and kill all the nobodies, you should level up in no time ^_^
valor and master form's best places to level up is the antechamber in mulan's world, there are those big horse heartless and they drop a lot of drive balls (to level up master) and they take a lot of hits (to level up valor) ^_^