A couple enemies that I've run into have been able to make themselves invincible. The first (I forget his name) most often pops up in the desert. He is a big furry guy. Anyway, if he oversouls he throws a hero drink on himself. You can't attack him or use magic. I've tried dispel tonics and they don't work either. I managed to kill him with items but..

Then there is Ultima Weapon. Thats him right, in the chocobo dungeon? He casts that 'Super Mighty Guard G' or whatever. Well, that makes him invincible too and he has like 33000 HP. Too much to take off with gernades.

How do you kill those guys?