Which paired Pokémon versions were first released outside Japan?

Pokémon Red and Blue were the paired versions first released outside Japan.

Japan originally received Pocket Monsters Red and Green in 1996, followed by an enhanced Blue version. For international markets, Nintendo selected Red and Blue rather than exporting the original Japanese Green edition. The overseas releases used the improved Blue version as the basis for the Blue game and became the familiar first-generation pair for many players.

The version split was central to Pokémon's design. Each game contained creatures that were unavailable in the other version, encouraging players to connect two Game Boys and trade. Completing the Pokédex therefore required cooperation or access to both releases. The international games also received localization changes, including new names, dialogue, and a different presentation of the game's title.

A common mistake is saying Red and Green were the worldwide launch pair. Those names correctly describe the first Japanese releases, but Red and Blue were the pair that introduced the core games to most international audiences. Pokémon Yellow followed later as an enhanced single-version release.