>>33940286ORAS gave us a bunch of new Megas, but I guess those should be compared to Z moves and not Alolan Forms since they are the main gimmicks of their generation.
Still, it would be weird for a side team to create entirely new UBs instead of the much safer, easier to make (I assume, at least) Alolan Forms. Unless those Ultra Beasts were just cut from the original Sun and Moon games.