Ix is broken yeah thanks to overray and stuff like Shredding Talons. No gMA is not a problem usually.

Raine would be your other best healer since she's one of the few characters in the game with healing circle but Mileena works fine. Her weapon that you can buy in the Exclipse shop is really good since it's an actual spell 4* and not those terrible physical artes they gave her.

They may have failed Kohaku in her melee department but seeing her juggling enemies with Burn Strike and Explode is fun. Hisui i've seen videos of his ranged artes and they look pretty fun but i don't have them so he's stuck on healing duty and casting Air Thrust on the side.

I don't like using Sara tbh. She jumps a lot and makes it hard to see her combo timings. Haven't tried her out again now that i have her 4*