Agrias: Guardbringer/Saint's Cross - TG mode - BSBX3
Ramza: MBD | Armor Breakdown - Shout + Chant
TG Cid: Powerchain | Full Charge
Yshtola: Ultra Cure | Shellga- Wall + BSB
Basch: BSB - Truthseeker
RW - Cloud USB
Here's what I would do for each character
Agrias - RW Cloud -> BSBx3 -> Guardbringer -> Saints Cross
Basch - BSB - Command 1 until triple imperil -> RW Cloud - BSBx2 - C1 spam
TG Cid - Wait til attack buffs are up, then unload. Can use other skill options since I have no idea what your hones are
Ysh & Ramza do their thing
Option for Ovellia if you need the buff slot for protectga though. Basch will outdamage Agrias since the en-holy on BSB entry. The 2nd entry will be on 7.38 potency vs Agrias' 5.88 potency. The OSB damage is moot since that's only 300k.
You can try and squeeze more damage from Basch by giving him Guardbringer. His C1 will be at 3.9 potency vs guardbringer at 4.8 potency.