I used the following team, which is probably less than ideal (and, frankly, I was lucky), but it did the job:
- Cloud (50): Galbadian Sword (2*++), Crystal Helm (4*), Hyper Wrist (3*) - Fire strike (4), Blizzard Strike (4) - Front row
- Luneth (34): Hammerhead (4*), Galbadian Armor (2*++), Hero's Ring (3*) - Dark Buster (2), Dark Attack (2) - Front row ~[I had no other good Support user]~
- Josef (44): Runic Axe (4*), Genji Shield (5*, 20/20), Hyper Wrist (3*) - Double Cut (6), Power Break (2) - Front row
- Linoa (46 then 47): Gravity Rod (4*), Gaia Vest (4*), Earrings (2*) - Blizzara (6), Sleep (6) - Back row
- Aerith (50): Judgement Staff (5*, 20/20), Crystal Bangle (4*), Angel ring (3*) - Cura (8), Poison (2) - Back row
Cloud and Josef were useful to kill the trash mobs quickly (if they ever managed to land an hit before me, I would S/L - as you can guess, it took me a lot of time to just kill them because of that). Gesper were a problem though, since I didn't have Bio, but I still managed to kill them without losing a medal for actions taken (and I met 4 of them during the 3rd stage, I had to ask Linoa to cast Blizzara on them - luckily, she leveled up right after). Aerith would kill the Forbidden with Cura (or Cloud would Fire Strike them).
Once again, it bears repeating: I was lucky during my fight against the T-Rex. I had to reload 6 or 7 times before both Poison and Sleep stick, and then I was able to Sleep him again 3 more times (out of 6 uses; Sleep has a 30% success rate). And again I beat it only thanks to Poison and Aerith successfully landing Seal Evil towards the end.
Your team seems to be vastly superior to mine, so I think you probably will have an easier time than me.