Also beat Gilgamesh Elite today, and reading Magic's post I see what I did wrong.
Bartz (Item use, help damage with occasional barrage)
Kefka (damage with Hyperdrive, secondary item user)
Luneth (damage with Cut Through/Raging Fist, tertiary item user)
Cecil (Provoke, defend, backup Curaja, emergency limit break)
Refia (Embolden, Curaja, Full Life)
friend Lightning - 576 attack (damage with Crashing Blow/Raging Fist)
So I didn't use Baraerora, which explains why Cecil was getting beaten so badly (wind weak with Golem esper). Heavy item use, used 5 Holy Torches, 3 Phoenix Downs, 1 Elixir, 7 Remedies (forgot Unicorn Horns). Lightning should have been replaced with Luneth instead since Luneth is immune to blind and paralyze. Bartz was mvp just by virtue of not dying and being tanky enough to survive X Slash (I'd use Holy Torch with Bartz on Vengeance turns and defend with everyone else). Everyone else died at least once except Lightning.
So yeah, half-assed preparations but I got it done. Not going to redo it for the twenty lapis I missed.