I don't necessarily think they'd be able to do much. Born from a paradox would make them toxic in times point of view. Maybe you can formulate an idea with that? You've already stated Weeping Angels hate them for this reason. Maybe that is what makes them stand out compared to the other races.
You don't need to be over the top to make an interesting alien. Hell, you don't need to be over the top to make a species unique from the others. Sometimes it's just a single trait or cultural difference that can make an alien species very interesting.