Which company developed Pokémon X and Y for the Nintendo 3DS?

Game Freak developed Pokémon X and Y for the Nintendo 3DS.

The studio created the games as the first installments of Pokémon's sixth generation. They were released worldwide on October 12, 2013, and moved the main series from sprite-based presentation to fully polygonal 3D graphics.

Pokémon X and Y introduced the Kalos region, three new starter Pokémon, the Fairy type, Mega Evolution, Trainer customization, and several new battle formats. Nintendo and The Pokémon Company published the games, but publication and development were separate roles.

Game Freak is often confused with other companies involved in Pokémon. Niantic developed Pokémon Go, OLM animated the television series, and Wizards of the Coast handled the early English-language trading-card releases. Game Freak remains the developer associated with the core role-playing games, including the original Red and Green as well as X and Y.