YOU WIN!
Mally had all Genji Gear on minus Genji Glove and destroyed the boss with Cursed Elegy being DARK elemental at 37000+ damage cap.
Brindle had both Zuu Beak + Shango and rotated normal critical 2-hit smashes and Heavy Smash.
Moguel had the Longinus and Blessed Ring; I rotated Adept, Might, Stout and Zeal Stikes with backup healing items/Stimulants.
Bosche had the Antares Deluxe, but never attacked and only used Procure and Megaelixir fixers.