You would have thought that before hand, doing a show on the Green Arrow that they would have thought the character good enough to use his own villains. He does have them, and they are not using them.
Instead they keep using ones from teen titans, and batman. They have worked him into being the centre of the whole DCU, changed other heroes so that they are a part of his world.
They should have just done a Batman show instead. They obviously don't think this character can stand on its own without making bad versions of other DC characters.