Try 2. Less tired and drunk I realize that both Gilgy and Seph don't need to retaliate and Seph can use double hit just fine. Incidentally, for Gilgamesh, Zach's glove is an equally good option as Seph's katana, go fig (I could still give him the Katana then put Seph's Katana Strength up RM on him but meh I don't have a good secondary weapon for Seph and I'd like to make sure flaming weeb hits 9999). Setup is
Faris (Box Polka[def down song], Tempting the Furry)
Seph (Flaming Weeb, Double Hit)
Gilgy (COME AT ME BRO)
Yuna (Shellga, Curaga)
Aeris (Strongwater, Curaga)
Gilgy come at me bro strats tear shit up for the most part, but unfortunately I neglected to realize that Baha's adds have MT physicals as well, and SG wears off too quickly to not have Protectga. Watching videos of people doing this fight I have no idea how they aren't just constantly healing. Also, I was incorrect - Shadow Creepers do defend against defense dropping, so the dance was a bad idea. The minor tweaks for next time are obvious, at least. Another issue I'm seeing is that since I don't have any way of targetting my attacks, Gilgy spends a lot of turns chewing through the adds instead of whittling down Bahamut, which in itself isn't that bad since it seems Giga/Petaflare are on HP triggers, but is obnoxious nonetheless. In light of this, definitely considering swapping out Double Hit for Indoor Spell on Seph, so he can build up Hells Gates since his damage isn't that far off of Gilgamesh's.
EDIT: Still S/Ling this try. Attacking Bahamut once before engaging the adds ensures Reta counters go to Bahamut. Consider not engaging the adds until the first Gigaflare charge, then using the splash damage from the cancellation + Flaming Weeaboo to take them down in a couple rounds. Doing this had the first wave die when Bahamut was just a little over 25% HP, so that will probably be the smoothest way of getting the 8 kills I need.
EDIT2: Ugh. Yikes. That is a lot of damage. I'll try one more time today but I have a feeling I'm going to need to spend Mythril to actually beat this.
EDIT3: After watching the video on the site Snow linked that beat the fight without SSBs, I realize one thing to try is swapping out Yuna for Mog. Apparently in addition to Regen, his Holy Lance SB adds DEF up and will help mitigate after I'm out of SG charges. I'll try this and give up for the day if it doesn't work, and revisit it tomorrow. I'm also really close to unlocking Luneth's MC1, and with some luck I can probably get his auto-haste RM before my attempts tomorrow.
EDIT4: Well, no SG charges, but someone with Aerith's SSB, and more of that is never bad. Let's do this.
E5: Nope, no go.
Things to consider:
DEFINITELY need Grimiore or Stone Skin. Be patient next time.
Come At Me Bro is nice, but with all the MT flying around I'm still healing like a Mofo all the time. Additionally, potentially unnecessary with regards to physical mitigation if I have Mog's SB up in addition to Protectga.
Tempo Flurry is 10 charges of 6000-7000 damage that I can't aim and requires Gilgamesh to be in Reta. This is usually fine, but if Flare kills it knocks Gilga out of Reta and then I can't do shit. Additionally, Waterja SHOULD be about the same damage unbuffed, and Terra can use Strongwater and has more durability here.
Considering, just to not blow more stamina than necessary, the following Setup:
Terra (Waterja, Thundaja... perhaps R1Meteo, if I can somehow scrounge up the Major Black orbs for it)
Yuna (Valefor, Shellga)
Seph (FWeeb, Indoor Spell)
Mog (Protectga, Curaga)
Aeris (Diaga, Curaga)
and then just blowing mythril on restarting the fight when I lose. Eventually I'm bound to get enough spell charges to make Valefor and Thundaga/Meteo Viable options, or enough defensive stats that they don't need to be. I guess my overall dilemma with that is, are the rewards worth spending 5-10 mythril on? The answer would be yes.
I could also blow mythril with my current setup, but I'm not sure if that'd be more or less expensive. It would certainly make landing on +Ability Charges useless, since running out of charges is not my issue here.