If we’re talking PvP, battling has constantly evolved through new abilities, even without gimmicks the way the game is played changed a lot through the years.
In single player they also changed a lot of stuff since gen 4, although the positive changes were mostly in gen 5/6 and the later ones like wild areas and the switch to “””open world””” were… not as well received.
I still think if copyright laws weren’t so oppressive, 50 years would be fair (And still a huge improvement from the current situation).
Maybe have it in tiers or something? First 10 years: full copyright - until 30: similar products allowed, but no blatant reproduction - until 50: reproduction allowed as long as it’s not for-profit - post 50: public domain?