Pokémon X and Y introduced the Fairy type.
Fairy was added in the sixth generation, becoming the first new Pokémon type since the introduction of Dark and Steel in Pokémon Gold and Silver. The type was applied to new Pokémon and also assigned to some existing Pokémon through updated classifications.
Its addition helped rebalance battles, particularly by giving the Dragon type a major new weakness. Fairy-type moves are also strong against Fighting and Dark types, while Fairy Pokémon are resistant or immune to several important attacks. These relationships changed competitive team building.
Pokémon X and Y were released worldwide for the Nintendo 3DS in October 2013. They also introduced Mega Evolution and fully polygonal 3D presentation to the main series. Fairy is the correct type name; “Light” is a common fan-made guess but has never been an official Pokémon type.