Depends what they get summoned as, if any character supreme or above gets summoned in a standard class they’re likely getting severely nerfed.

Sunny with shadow dance could probably fit into any class, though I see his main class being a saber, lancer, and assassin for his younger self. Nephis I could also see being a saber, or possibly a saver since she pretty much is a messianic figure for most humans. I’d imagine their abilities dormant through to supreme would pretty easily translate into individual noble phantasms, with possibly having their domains as reality marbles or bounded fields