So Chaos is kind of a butt, given the lack of Affliction Break for the CM and his Omni-Resist. However, at a suggestion in Discord, I tried using Grand Cross for Omega Drive spam on Garland with my shortage of relics. Not only did I pump out the damage I needed, I also found out that Ultimate Gaze, the Stop-inducer, is absorbable by Grand Cross.

So an easy budget strategy is to bring Garland or Master (whoever you can get a better weapon for) with Omega Drive and their respective self Boost (Dark Bargain/Meteor Crush) and build the rest of the team for surviving (Double Healer, Dancer Echo, Support Wol or Utility White WoL). Put Tifa's earring (Stop Resist) on Echo or whichever Healer has lower MND, and the strategy speaks for itself from there.

I recommend using Celes's BSB2 as your Grand Cross source, since it comes with another self-ATK buff to strength Omega Drive even further. I could make Garland pump out ~28k per action with Omega Drive, and so much of Chaos's offense is ST Magic that it saves a lot of healing pressure.