>>49844433They've been in basically every game and spin-off other than SwSh, often used as a Pokemon's powered-up state. They're less of a battle mechanic, and closer to a form change for that specific Pokemon. I have a hard time understanding why you would remove them, any more than you might remove Landorus T or Giratina's Origin form.
It also just sucks to see good Pokemon like Mega Altaria or Pinsir completely removed.