Well this was a dungeon I never expected to clear. Mrah andI cleared it together on a whim last challenge dungeon and that was fairly nonchalant. I remember trying it many times with her previously to no avail. While she had completed it prior, I was unable to defeat Sonia Gran Reverse with any of my teams (ily Sephiroth). That changed when ALB came tumbling out of the REM on his horse-dragon homunculus thing.
F1: [P1] uses Perseus, Kill
F2: [P2] uses Dios, swipe
F3: [P1] passes, [P2] Dios / Poverty Vaan, kill
F4: [P1] uses Verdandi and Ra (for time extend), kill
F5: [P2] Clears locked orbs. [P1] Dios, kill
F6: Stall until absorb goes away, Dios, swipe
F1 can spawn as either Lightning Holy Dragon (who is nice and gives you 3 turns to kill him) or Chaos Devil Dragon (who preemptively binds 3 turns to all light monsters). I brought Perseus for the sole reason of bind clear (lacking other options), and because I’ve experienced that bind before.
I brought my ADQXQ team in without a bind clear.
..quick and easy death.