Preparations:
I did not upgrade any new equipment. Give Light and Vanille your best two bangles. And I would actually recommend giving Fang a Doctor's Code instead of a bangle (didn't think of it until just now). Set the Battle Speed to Slow. Make sure you have at least 10 Phoenix Downs (probably 15 to be safe), and a few Potions lying around.
NOTE: DO NOT UNDER ANY CIRCUMSTANCES SELL ANY DOCTOR'S CODES!!!!!
Basic strategy:
STAY ALIVE!!! Start in SAB/MED/MED and use Slow once you have charged 2 ATB segments. Pray that one of them lands and then switch to SEN/MED/MED. Vanille and Light will die a lot in this fight. Your priorities in order are:
1) Make sure Fang is in SEN mode when Bahamut starts an attack. This increases her odds of survival and charges the Gestalt Gauge.
2) Make sure Fang is at at least 500HP.
3) Phoenix Down dead allies. (This can take precedent over #2 if you know you have some time before Bahamut attacks again.)
4) Get Slow on Bahamut.
5) Get allies in green.
6) Use SEN/RAV/MED for a round or two.
Few tricks that might help you prevent Fang from getting launched. If you time a Potion at the right time, Fang will stay on the ground. Also, if you use Mediguard right before the attack lands, she won't go anywhere.
This really isn't that hard, but there is an element of luck to it. If Slow does not hit on those first 2 tries, it will be difficult to recover.
Bahamut
HP - n/a
Magic - 310
Strength - 310
Elemental Vulnerabilities
All normal
Status Effect Vulnerabilities
Slow, Provoke: 100% (yet they miss all the time)
