I play JP so not everything may be 100% accurate. Mages #1 - Exdeath. He has dual cast and meteor which makes it easy for him to hit 999 in arena twice per turn, even with a low magic stat. #2 - White Knight Noel. Despite not having dualcast and other super powerful spells, he's tanky and has a chance to counter with magic so he can do even more damage. He also has a giant sprite which makes it hard to target the units behind him #3 - Arc. Like Exdeath, he has dualcast so he can hit 999 twice but he's really squishy and he may die often. Physical attackers #1 - Noctis. Noctis has powerful attacks and his flask skills are perfect for arena. It casts status ailments/stop which can really screw up the other team, making it easy for you to win. #2 - Gilgamesh. Gilgamesh can equip many weapons so he can inflict statuses with them. His "divider" skill has a high multiplier so it can hit 999 damage fairly easily. #3 - Luneth. Luneth has a good AoE attack move and innate dual wield which can be useful, especially if you dont have a lot of TMs. To add on, Luneth has innate resists to status ailments which can come in handy if you face an enemy with status weapons or Noctis. #4 - Lightning. Lightning has many AoE moves, which are great for AoE chaining to surpass the 999 damage cap. #5 - DKC. He may die quickly, but if you can support his heals, he can easily take down the enemy. #6 - CoD. She has a great innate man-eater so she can heal high damage, even without OP gear. Give her diablos so she can use darkside for AoE damage if wanted (or use her innate barrage but you may fall asleep waiting for the attack animation to finish) #7 - Bartz. He works well with a petrify weapon + gale barrage to petrify the enemy team. Tanks #1 - Cecil. He's like impossible to kill... And he can buff your party and heal #2 - White Knight Noel. He can also do damage while tanking. #3 - Snow. He can counter with a high rate so he can be putting out damage. #3 - Demon rain. He can counter with a high rate so he can be putting out damage. #5 - WoL. Give him golem cane + sleep dagger and use bladeblitz for status ailments. Healers #1 - Refia. She can buff, heal ailments, cure, and raise. Refia also has an innate resist to ailments. #2 - Santa Roselia. Roselia can counter heal so if you're in a bad situation, she can heal your team even between two enemy turns. #3 - Tilth. Tilith has OP buffs and she can AOE cure every single ailment with a heal, which can help. Support units won't be used too much, as you'll mostly want to run attackers and mages to kill the enemy as quickly as possible. Hope this mini-guide helps!