This fight is pretty straightforward so long as you have a way to prevent Meteor+ (Behemoth King uses this when it is in force time, and it instant kills you)
Besides this attack, the bosses don't get any bonuses in force time so you might as well let them enter force time and then finish them off.
Setup
Everyone has U2 passive equipped.
Aranea 5/5 UW FR30 (Shantotto LDCA)
If you don't have Toto you can set Quina call for the trap which will BREAK and delay the boss when it warps turn. Or use Mog or Wakka call and hope to land confuse.
Iris 5/5 UW FR30 (Lunafreya LDCA)
Dorgann 5/5 UW FR30 (Seymour LDCA)
Remove Buff Speed Up on Dorgann
Bahamut summon is to give Aranea full EX meter inside summon mode. The BREAK bonus is also nice to have since Aranea and Dorgann will keep BREAKing every turn.