Karen wears a very girly nightgown. It could pass for evening wear in some places, although those are places Karen should never go.

Cinnamon and Radd both sleep in their normal clothes (which for Radd is shirt+shorts so I put that). Cinnamon because she doesn't sweat, so there's not actually any particular reason for her to change her clothes ever except if they get dirty (or she just wants to wear something else). Radd because, uh, his clothes aren't actually removable.