X and Y weirdly enough. Just to bully modern Gamefreak a little more, when Sword and Shield came out, part of their excuse for cutting a lot of the pokedex was the switch to Switch and needing to update too many animations. But my boi X and Y made the switch from 2D sprites to 3D models from scratch, and they got everyone. But besides that I liked the region, the cozy settings and focus on fashion. And megas did so much, giving new life to previously underwhelming but well designed fan favorites, and also reigniting the fanart scene with the burning question of “what would your favorite pokemon’s mega look like?” Exciting times in the fandom.