Chewbacca is correct, and master form for when he his you up ... ir about to hit you, his hits are predictable.
You dont use the forms , you use the abilities you get from them, like how you can slide from wisdom form... you get to glide after leveling up final form
It is in abilities, you can learn the abilities for your person, sora, by leveling up your forms. I leveled up the easy way.
Like the valor form.... i think it levels up based off of hits right? so you just stroll around a lot in valor form in a world with lots of heartless. smack the bejeebers out of them and hit a save point to recover gauge. for wisdom form i went to disney castle and I went to TimelessRiver place.
wisdom based off of heartless kills, forgot about master form.... collect stuff I guess? Final form I strolled around the nobody world a lot, will AMAP As Much As Possible good old times