Wouldn't that be Winged Slayer (Sword move, level 10)? It IS a 3x3 grid attack after all.

A leveled magic attack (3x3 grid again)

Or the Big Bang fist attack I (fist rank 40), another 3x3 grid attack. All of those, assuming they're powerful enough, would KO all the enemies in one move.

EDIT: LMAO, I didn't see 'stat' XD

I can't put any specific number, but if you can clear CoO2 with minimal trouble, you SHOULD be able to make it through CoO3. Usually the first time you visit, you're going to need a lot of chain attacks (so have everyone connect their attacks to at least one enemy thel ast one attacked) with the finale of a 3x3 powerful grid attack. If you can't at least kill some of them that way, you need more training, though if you can get really close, and survive their attack, you might make it.

Whooo, that's not good.

Study This Threaad. Should give you an idea of how to optimize your damage dealing.

The thing with these galactic demons is that they have high DEF and RES (they also have 150% aptitude for both, though they have no items equipped). Once you pass the critical 'no damage' point though, you'll start doing a decent amount of damage to them.