Bahamut has a whopping 60m HP but you can still take him down by combining BT mode, summon mode and a wee bit of Awakening spam from Machina :)
Timestamp
Party setup at 10:40
If you don't have Raines LDCA use Onion Knight. If you don't have Quistis LDCA use Seymour.
If you don't have Leo LDCA use Cait or Prishe LDCA
0:00 Setting Up
The hardest part is to reset until you get a turn order of Selphie, Machina and Garnet. Everything is smooth sailing after that since Bahamut will never get a turn.
The idea is to setup with both Selphie and Machina, then have Garnet use Raines call to pull them back so that you can swap Selphie for Ramza and then go to a maaaaassssive BT mode with Machina
4:07 Machina BT mode
6:25 Summon Mode
I used Shout on Ramza's second turn inside Summon mode so that he can jump his turn forward from the high turn rate. This allows him to participate in launches.
8:29 Finishing Up
Right at the end, Machina will get final turn inside summon mode. I just go LD into Awakenings to finish Bahamut off.
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