Catastrophe and Doom Bringer
Chaos. I think LuCiel and Add are the most unhinged characters in general, so choosing their most fun and chaotic classes would suit her.
Celestia and Lord Azoth (Bonus: Richter)
Smart baby would go for smart looking designs. Her being a high power mage just makes sense (even tho they are nerfing the shit out of Aisha). It also make sense for the best girl in fromis to play as the best boy of the party.
Devi and Code: Antithese
Do I even have to elaborate on this? Just look at them. Handong and these three are the definition of power. All of them could step on and I'd apologize for being in the way. I wanted a brawler for her, but the designs just fit her so well.
Rune Master and Flame Lord
Do I just want to see Saerom dressed up as a hot pirate captain? Maybe so. But also consider: fire. I may be leaning more towards Rune Master as Elsword is the "leader" of the party. Honestly I'm just going off of gut feelings at this point.