For context, not only was it the first time this has happened, it was the only time it happened and resulted in nerfs for all of these Pokémon across the board.
Smeargle can no longer copy Dark Void (and several other moves) (up until this point it could copy any move in the game) (single handedly got Dark Void nerfed).
Kangaskhan lost several moves from it’s moveset and got it’s mega ability nerfed.
Salamence got it’s mega’s ability nerfed.
Primal Groudon no longer exists (on virtue of basically removing Megas from existence).