Angra Mainyu

[Indigo Truth]

How i beat it:

Equip 2 people with dark knight and have them learn ALL the proofs, then you be basically immune to all status elimination. Also if you have it equip them with an accessory that doubles their HP and equip them with a Garment Grid that has Break HP Limit. Then equip the other person with Alchemist and a Ribbon (and same Grid etc) You want to have learned Phoenix Down, X-potion and Mega potion and elixer. Keep using your dark knights 'Darkness' ability and also try 'Black Sky' if you have mastered it. Because darkness takes off your HP, make sure you are using Mega potion to revive them, and Elixer if they need it after using black sky. Part of you team will die but make sure to keep healing them and take advantage of the fiend healing his arms.

It takes a while, but it works =]

 

[TherathxRikku]

I managed to beat it at level 42 with the Dark Knight and Alchemist dresspheres. Just spam Mega Potion and Darkness.

Even with that, you can still screw up if you get your timing wrong. When he regenerates his arms, you always want to time your Darkness after he regenerates one, because if he regenerates after you used Darkness, it will only hit the body and you risk him using that explosion move, forgot what it was called...