Going without either is typically seen as rather lewd behavior in most cultures. In the episode ' Birthmark', when Slade tears off Raven’s clothes, it is clearly shown that she does not wear a bra, or underwear of any kind underneath her leotard.This is further helped by the fact that the show arguably treats it as if she really was naked, with Raven covering her breasts and Robin’s fist conveniently placed over her groin area.
In the episode ' Episode 257-494', when Beast Boy steals Raven’s cloak, she reacts to it as if she had just been stripped naked.
