Help me build a Bahamut killing team.
If you can't one shot Bahamut, then you need to have some members survive, then AoE revive the dead on round 2. From your listed units only Rikku has AoE revive (re-raise won't work against megaflare because it's a multi-hit attack). Here's some example stats for Bahamut's turn 1 megaflare hitting Rikku:
With 50% mag break from your 9S, a 70% SPR buff from your Wilhelm (enhanced), and while GUARDING, Rikku will take:
7,981 damage at 300 pre-buff spirit
6,411 damage at 400 pre-buff spirit
5,358 damage at 500 pre-buff spirit
etc (Bahamut has 790 base magic and turn1 Megaflare has a 21x modifier if you want to math it yourself)
So basically, gear your Rikku so that she has enough spirit and max HP to survive the turn 1 megaflare, then go against Bahamut and turn 1 use:
Rikku -- Guard
Refia -- Guard (she needs enough spr / hp to survive too, but if Rikku can, she can easier)
Wilhelm -- Spr Buff
9S -- 50% mag break
Trance Terra -- Guard if her spr/hp is high enough to survive the megaflare, or just chaos wave for some damage
Trance Terra Friend -- see above
So turn 1 with the above, if Refia and Rikku survive, you should win. Bahamut will kill everyone else.
Turn 2 have Rikku AoE revive, then have Refia dualcast heal
Turn 3 have both Terra's magical activate (refresh buffs etc with the rest of the team)
Turn 4 break Bahamut's SPR with 9S, then chain both TTerra's dualcasted awakened chaos waves, which should kill Bahamut
Turn 5 chain chaos waves again if Bahamut lived, and if he still hasn't died after 2 turns of double TTerra, you need a better TTerra friend because he's about to megaflare your face again
Other options are trying to cheese it with a Garnet enhanced friend on Bahamut and capping the friends Bahamut summon, wait a few weeks until Mistair, or build a glass cannon team that can one shot bahamut on turn1 (TTerra won't work for that because of her setup round).
