>>33618275He's not a destroyer of regions yet, he hasn't killed a legendary yet in SM.
Once that happens anything is possible.
Actually, thinking about that for a moment, what do we call Pokemon who defeat Ultra Beasts. We have Mega Slayers, Legend Killers, but what about for Ultra Beasts?
Beast Crushers? Ultra Executioners? Beast Butchers? Ultra Exterminators? Beast Breakers?