>>44430701Mega trials.
How to get those stones you ask? Rather than finding them randomly throughout the world, you start a quest to get your keystone.
Various little spots throughout the world for each pokemon with a mega.
Trials similar to a mixture of an alolan trial, plus the pokemon master from lets go.
Puzzles to solve, and then a totem who gives you the mega stone once you've beaten them.
Only able to use the same pokemon as the stone you're going after.
Gyms give a tm, a badge and a z-move.