Major Numerus (Final Fantasy X-2 International + Last Mission). From what I've been able to ascertain, without the "cheap" alternative of invincibilty (via Miracle Potion), this boss is pretty much impossible. Too bad the game is exclusive to Japan.

Quote Originally Posted by Throneof Dravaris
Can't remember if Cait Sith's auto kill dice worked on bosses...
It does. It's hardly necessary, though.