The original Japanese Pokémon Red and Green games were released for the Game Boy.
Nintendo's monochrome handheld was the platform that introduced the Pokémon role-playing game series in 1996. Despite its limited display technology, the Game Boy supported a large world, turn-based battles, a Pokédex, and link-cable trading between players.
The first games were designed around communication between two Game Boy systems. Red and Green contained different Pokémon availability, encouraging players to connect their systems and trade creatures that could not be found in their own version. This trading concept became one of the defining features of the franchise.
Later Pokémon releases appeared on the Game Boy Color, Game Boy Advance, Nintendo DS, and other systems. That history can cause confusion, especially because Pokémon Yellow used the Game Boy Color's enhanced color capabilities while remaining compatible with the original Game Boy family.