Chaos is skilled with magic attacks. Chaos will attack with fire, ice, lightning, water, wind, and earth magic, so raise your party's SPR and resistance to each element before the battle, kupo!
Also be sure to have countermeasures for attacks that can inflict instant ko, paralysis, stone, and stop, kupo!
Chaos will boost its own parameters, so prepare methods of removal such as fingersnap or dispel, kupo!