This was an Issue in Sword/Shield, though im unsure if it was also in U.Sun/U.Moon, but yeah, this feels like an evrn more barbaric way of inflating sells, i really thought after Arceus they would realize this two game system just, does not work anymore, and forcing this game diversity is a bit of a double edge sword, on one hand, if a pokemon you like is in your version, GREAT! But if not then you are forced to either 1. Trade randomly. 2. Get a friend who has the sibling game to trade with you, or 3. Shell out and buy the other game, I really hope Game Freak realizes this and tries out Single release mainline games, but, probably not, after all,

"Business is Booming!"