Bring Back Event Exclusive Moves

LeBarBURR

Since V-Create Rayquaza is no longer possible to obtain after Sword & Shield, it would be interesting to create other similar events, such as V-Create Gouging Fire, Dragon Ascent Ho-Oh, even Tera Starstorm Arceus

Acornyo

I think they wanna keep moves exclusive to Pokemon to make them feel special. I dunno how else to put it, but I feel like that's the main reason.

If more than one Pokemon has a move, people think of it as a regular move, so the Pokemon in itself loses some value, as some people just want it for the attack.