oh boy oh boy, i'll do mortal gods and dsrk so let's go:

Raidou Kuzunoha: this one is tricky, as I'm torn between samurai and gunbreaker, but i think i'll go with gunbreaker since sword + gun and it fits him thematically more than samurai, i feel

Narumi: Machinist with some ninja cross-class in there (as a homage to his past as a spy)

Gouto: looks you dead in the eye carbuncle

Tae: arcanist, if only bc i feel she'd vibe with tataru and bc i feel it fits her?? Yeah

Nagi: Samurai, definitely, she feels like a good fit for the class in general, as well as her dramatic vibe lmao

Dahn: ninja, hands down. I mean he pretty much is a ninja anyways...

Okay, self-indulgent time:

Atsuo: Samurai again, as he is pretty orthadox in terms of fighting, that or gunbreaker, sticking to raidou traditions

Shun'ya: dark knight for.... mortal gods spoiler reasons /shifty eyes

Rin: As Nahobino, he'd be red mage, as a human, arcanist, definitely

Aogami: steeples fingers. okay, either monk or paladin but, like, more magic in there somehow

Tsukuyomi: Ninja or... dancer. Yeah. Ninja-dancer. Yes.

Abdiel: paladin. No contest. The most anal paladin ever.

Yakumo: Reaper or a really assholish samurai, which are apparently abundant in kugane so

That's all i have the brainpower for right now but hhgh hope you enjoyed that!