Watch out, Radioactive Man! It's a bumped thread!
As far as I know "cosplay" is just for "fun" and is not sexual. the goal is for people to usually make thier own and dress up in authentic and detailed reproductions of fantasy clothing. There IS a fetish involving people dressed up in caricature cartoonish animal customes, that I don't really understand. I think that it's more about the anominity of the experience than the custome itself, as a giant shaggy dog head diguises the wearer and you can't tell gender, race, age, or if it's your next door nieghbor or priest.
there is a fetish of sorts for costumes that run anywhere from non-seually, but commonly seen as sexual (maid), semi-sexually, but usually not seen as sexual (doctor) and non sexual and not usually seen as sexual (police officer). All of these things seem to have in common themes dealing with people's professions (it's debatable if cheerleader is a profession.) They are more like kink than fetish as the subject of lust is still the person and not the object itself.
anyway.... I wouldn't call it a fetish, but I suppose the comic book nerd in me has some intrest in seeing superhero sex costumes, and I've browsed it once or twice. didn't come up with too much though.