Pokémon X and Y (2013)

Best: The fairy type. Pokémon’s type chart is the mechanical backbone of the series, but it remained stagnant for more than a decade; the biggest previous shakeup of its formula came back during Gold and Silver, when dark- and steel-type Pokémon joined the mix. That finally changed when Pokémon X and Y introduced fairy-type Pokémon. Though it was weak to poison- and steel-type moves, it served as an effective counter to the then-overpowered dragon- and dark-type Pokémon. Plus, it put longtime players on their toes for the first time in a while.

Worst: Mega evolutions. Pokémon can evolve, sometimes twice. With every new form, they’d gain a notable stat boost, and a cool new look. Pokémon X and Y introduced probably the most ill-advised twist to this mechanic: mega evolutions, which temporarily allowed some Pokémon to evolve past their final stage. Though mega evolutions only lasted for the duration of a battle, it gave a significant stat boost to the Pokémon, effectively turning it into a trump card. Even worse, there was very little stopping you from just…doing it all the time. By the time X and Y rolled around, there were hundreds of Pokémon you could choose from to make your team. But why do that when you could just choose one of the 50-odd mega evolutions?