Anima? I think that's the one you mean right? Well, you should use your aeons against it. What I do is weaken it with my least strongest aeom first, then wait until it uses Oblivion, then send out my strongest aeon, cast Haste an' Protect, then just wail the pee out of it.
What do you do when you fight it? I can try to help you improve on that strategy if you don't like the aeons.
Baby I like it.