There's two ways I would consider balancing most Raid teams - by Co-Abilities, or by Defense Down/Proximity Damage Up effects.
With Co-Abilities, you're looking to stack four offensive Co-Abilities if you don't have survival issues, which most players shouldn't as the damage in this fight is tied mostly to attacks that happen if the group fails to destroy an orb. Sword/Blade/Dagger/Wand/Bow have the relevant Co-Abilities for offense, while Lance/Axe are for survival and Staff is largely useless (healing comes mostly from Dragons and Shields in a Raid).
With buffs/debuffs, you're generally looking for guaranteed or high-odds Defense Down. It stacks all the way to -50% Defense (which is double damage!), and helps the damage of all 16 members in the Raid, no questions asked. The next best thing is area-effect offensive buffing like Attack Up or Crit Rate/Damage Up. The problem with buffs from a source like Sinoa or Elisanne is that they only apply to your party of four - not a big deal if you've got the best party in the room, but something to keep in mind. When it comes to area effect buffs such as Odetta's second skill, you can hit as many targets as you can get near - including all of the player controlled characters if they're all focusing on hitting a specific target like an orb.
I'm running Marth/Vanessa/BowEzelith/XuanZang myself, with a strong lead (MUB 5* Elemental Sword with MUB Cerberus) and three AI that can apply Defense Down. Since I don't own or expect to own Sarisse anytime soon, I have BowEzelith maxed out for the huge Skill Haste Co-Ability, and Vanessa is maxed as my go-to HMS character. I end up around 30% Dragon Prep/21.5k Might if I don't bloat with my two MUB Phoenix (0UB Cerberus and 0UB Agni are my #3-4 options, worth about 400 less Might each), and in the ballpark of 9000 total Strength.
