DETAILS- I use seph, wakka, cloud, aeris, rydia. all 50 I have seph, wakka, cloud and rydias five star relics. Aeris has a 5 star staff but its not her character specific. My armor is Genji helm, genji armor, and 2 of the 5 star robes for aeris and rydia. wakka uses a 4 star ++ helm.
WHAT YOUR UP AGAINST- Trash- about 3k hp, my autos hit for about 1k against them on average, and they hit for about 1k themselves with some abilities doing 2k- they also have nasty status attacks. Even abusing save load its nearly impossible to beat them without taking damage.
iguanas have about 50k hp. They have a 50/50 chance about of auto attacking for 1200 at least on any of my guys, or using the fire breath which has the petrification chance and does about 500 damage to everyone. The petrification chance was about 20% per hit per character, meaning the odds are that one guy was gonna get stoned each time.
Seifer- supposedly 140k hp or something like that. his auto attack double hits for about 1400 and uses fira for about 700 to the whole team. 3500 damage to your team from fira, 1400 from auto attack, which is an average of something 2500 damage per turn that you will have to heal through for a long time.
I repeated floor one, using no abilities to save up all my soul breaks on all my guys cept aeris. I ended up with about half health when i started iguanas but with all my abilities available.- Braver hits default for 8k, wakkas status reels hits for 5500, sephs hells gate hits for about 6k and rydias eidolon 2 hits for 6k. After wakka's SB armor breaks one, then they take apx 20% more damage.
Unless you don't use a healer, that should be nearly max damage possible per turn, and 2 full rotations can kill one. after using the final soul break for each guy, the last dude probably only takes another round to kill.
Having defeated the iguanasaur things, I started the fight with seifer and there is absolutely no way that my team, and I expect any team, could have enough healing to survive long enough with fira's damage output.
So if you don't have all 5 star relics on all guys, don't bother trying. If you do, I still wouldn't bother trying. You aren't gonna kill these guys with retaliate or quake.