What was the first Pokémon main-series pair released worldwide on the same day?

Pokémon X and Y were the first Pokémon main-series pair released worldwide on the same day.

The games launched on October 12, 2013, for the Nintendo 3DS. Before X and Y, Pokémon releases generally reached Japan before North America, Europe, and other regions. A simultaneous global launch made the sixth-generation games a shared international event.

X and Y introduced the Kalos region, which is heavily inspired by metropolitan France, along with 72 new Pokémon, the Fairy type, character customization, and Mega Evolution. Their worldwide timing also reduced the risk that players in earlier-release regions would reveal major game details before everyone else could play.

The wording matters: X and Y were the first main-series pair with a simultaneous worldwide release, not the first Pokémon products to launch internationally at exactly the same moment. Later main-series games continued the global-release approach.