With that said, the bonus characters are pretty good in general, with stats and aptitudes close to generics of tier 5~6. Conceptually it's a bit weird that the master learn from their pupils, but whatever. *Just in case you don't already know, you can learn spells (Fire, Star, Heal, (de)buffs etc, but not weapon or innate abilities like Hurricane Slash or Crimson Flame) by having a master stand next to their pupil and cast a spell they have until you reach lv 1 with that spell for your master (now they can cast that spell on their own, without needing to stand next to their pupil). You should also consider including a few knights in your party just for their throwing stat. Eventually you'll also want to create a thief to steal items, since otherwise you'll be stuck with 50% chance for stealing at most. Again, that is mostly an issue for spellcasters, the others will learn weapon skills normally (weapon mastery in staves increases dmg, range and aoe of spells, but you don't learn the spells themselves from it). You probably want to at least create a mage/skull and/or a healer pupil* for your spellcasters, otherwise you'll be stuck with the characters' innate skills (usually 3 in total by level 50+). If you only and exclusively use the DLC characters, I suppose so, but I don't see what's stopping you from using generics at any point.

Disgaea 2 dlc skills