Board Thread:General Discussion/@comment-34147304-20180110000100/@comment-24922135-20180113204912

That's not true at all. Ben has, at most, about 100 aliens unlocked by the end of Omniverse. He has used just over half of those, and it is heavily implied in UA that he passively scans species he meets (presumably from the Milky Way) to unlock them, but judging by their lack of use they're probably the human-like species with no particular powers. They were probably also locked again in OV since Ben never used them by accident.