I think another kind of grouping which can be used is
- unarmed division
- melee weapon division
- projectile weapon division
- magic division
- free for all division

the name of the divisions pretty much explain what it is,
while free for all division are pretty much like the megaton division,
it would consists of characters that have more than one fighting type.
i.e. : the ninjas from Naruto series would fall in to this category, cuz they use unarmed, projectiles, some used swords, and also ninjutsus..

Just a hundred rupiah from me..
it really isn't much..
haha..