>>52959419Gameplay.
Not just the battle engine, but even all-out-of-battle taming aspect.
Dunno, when I was a kid watching the first season, I always hoped that being a Pokemon trainer would have shit like dealing with an asshole and uncooperative Pikachu, having to do some light vet work, actually teaching / training them and stuff.
Even back then I knew the GB couldn't do that much more, but each time a new generation was release it would finally make a big jump into making me feel like I was going through the same kind of adventure than Ash.
The GB games and their technical limitation just shaped everything afterward way too much.
So I dunno, I'm getting old but still I'm vaguely holding on the hope that some genius dev out there has thought of an actual worthy concurrent/re-imagining to pokémon that isn't just a variant of the GB games with a fresh coat of paint and a bunch of gimmicks removed/added, like all romhacks or ThemThem do.