>>54620192XY had a better Battle system.
I think Z Moves were a bland idea to build a whole game around. They tried to “fix” the issue of Mega Evolution being elusive, and made something really generic that everything could use.
There’s nothing like finding different Mega Stones across Kalos, and lrarning each Pokémon’s unique upgrades. Every system after XY has been some weird attempt to undo that, winds up being forgettable.