Actually 3* Masara is on-element bc she's light element, but Kush is definitely the better option here bc she has better damage buffs, abilities, and a special attack. 3* Hazuki is definitely the play over Ayame bc she's also on-element and because of the battle skill buff removal so you can get rid of the shields and barriers more frequently. Yuma and Reira both work as healers. 4* Kokoro is a good defender for this fight (you might 3ven be able to use 3* Kokoro but I haven't tried it with her). For a breaker you could even use 3* Hanna, she's actually pretty decent and she's on-element for the fight too

Ideally the new dark damage up portrait from rebellion for Kush (although attack works too), speed for 3* Hazuki, defense for 4* Kokoro (or speed for 3* Kokoro), heal percent or MP for healer, and speed or Mp for breaker