I am enjoying this way too much at seven in the morning.
Belial: Jackets, button-ups and jeans. Suits. Whatever fits the occasion. He's aware of how he looks and how he wants to come across, so he's maybe a bit more fashion conscious than your normal demon.
Euterpe: Casual, almost all the time. Dresses are cool, but she prefers jeans and leather jackets over your general girly fare. She's toured a hell of lot of time with guys on her rock escapades and picked up their style somewhere in the eighties, morphed it a little, and carries off the the rocker chic look as much as possible.
Psych: John, suits. Casual is still extremely uptight. Jane... er, drag. But nice, classy drag. (Trust me, if she had a different body she'd be going all out.)
Coffee: Casually, Tennantminus (or plus, but only on Occasions) the Doctor wardrobe. Jeans, zip-ups, hoodies; generally, the kind of clothing you would shrug on right after rolling out of bed and right after having your first cup of morning java. On those Occasions where he does dress up, he wears nice suits -- if a bit kooky, and slightly ill-fitting. Think put-upon nine-to-five business official who has to do all the coffee runs for his coworkers.
Jophiel: He's a pretty laid-back angel, wears suits if he has to, but otherwise normal. Unless he decides to go the transvestite route for he day, which, you know. Anything can happen.
Jersey Devil: Ever the gentlemen, JD's very clean and hygienic and doesn't tend to trot (hah, trot) around in jeans much. But he does run a gas station in the middle of nowhere, and there isn't much opportunity to dress up, so it's pretty casual for him. A nice t-shirt and jacket won't go amiss, same with his de-aged self.