Nina got a mega evolution in the pokemon mystery dungeon campaign i play! She ended up finding a shrine that was used to make megastones (not that she knew that at the time) and ended up making her own through some keen puzzle solving! she got it attached to her poison barb, though when a megastone is used, it fuses with the owner, which is why you dont see it here.

Art done by the incredibly talented  wakamolez!