Actually Starlight is a weird case because she's less not beaten by the events around her and more like the episode realized they didn't know how to beat her so they came up with that contrived wasteland scene. She's stuck in the border of a left character and an actual Mary Sue. Anyways the only Mary Sue I can think of at the moment is that Kelpie from the comics.Actually I think the better word to describe Starlight is The Scrappy.