What were the original Japanese Pokémon games called before their international release?

The original Japanese Pokémon games were called Pokémon Red and Green.

Game Freak and Nintendo released Pocket Monsters Red and Green in Japan in 1996. The two versions shared the same central adventure but contained version-exclusive Pokémon, encouraging players to trade through the Game Link Cable.

Internationally, the pair became Pokémon Red and Blue. The overseas Blue version was based on an updated Japanese release whose artwork, script, and code were used for the international editions. This is why many players who began with the franchise outside Japan know the first generation as Red and Blue.

Pokémon Yellow arrived later as an enhanced version inspired partly by the anime, with Pikachu following the player. It was not one of the original Japanese launch pair. The Red-and-Green naming distinction is one of the clearest examples of how Pokémon releases differed between Japan and other regions.