>>38689130None of that makes them inherently legendary, and not even all of them have stat totals reaching the typical lesser legend ones (oddly enough Naganadel has a smaller stat total than the rest).
Functionally they work like them in battle I'll agree, but they aren't legends officially, and that's the final say on it. They don't have the biggest flaw of legendaries though imo, which is that they take up a whole dex slot for a Pokemon that there's only one of in the entire game, killing off a lot of the variety available once one is caught. The original 7 UBs spawn infinitely, often as common run-breakers. The only UB line in the series that's limited to just one is Poipole.