Each side has 1 Gunner, Paladin, Dark Elemental, and a White Mage. The White Mages will be spamming Shell a lot, which can be an issue if you're using mainly a magical team. Paladins will be using Taunting Blade, while Dark Elemental uses Bio often.
Most of their damage are physical, and they have negative physical resistances, so Tidus with paladin sub job is pretty good here.
Since this is Auron's dungeon, the enemies are weak to slash and ice. Units like Gilgamesh and Lasswell can help fill that role if you don't have Auron. Mages with good aoe like Mediena or Ildyra can still work quite well to deal with multiple enemies despite the Shells.