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the franchise continued in the direction of Gen V - instead of introducing metagame gimmicks to throw away each generation like Megas and z moves, they further refined the gameplay while adding new pokemon.
Triple and rotation battles were a good example of this - new ways to play without completely dominating the metagame. Hidden abilities - weather wars aside - were also a good way to enhance existing pokemon.
Keeping things sprite based but increasing in complexity would have kept things charming and not deplorable like GF's current 3D attempts. We still had 3D scenes even from way back as Diamond and Pearl, but just compare the richness of the Marine Tube in BW2 to the environments we've seen in SwSh.
And while casualisation did start in Gen V, just compare the average dungeon there to what we've got now. Also, we would have kept challenge mode. At least we would still have a modicum of challenge in single player mode. Things like ultra necrozma are the exception rather than the rule in the 3D era.
