Pokémon Red and Green were originally developed and released for the Game Boy.
The handheld’s Link Cable was crucial to Pokémon’s design because it enabled players to trade creatures and battle friends. Trading was not a side feature: certain Pokémon were exclusive to one version, so completing the Pokédex required connecting with another player or using another cartridge.
The original games used the monochrome Game Boy’s limited hardware, yet their turn-based battles, exploration, and collecting system supported a remarkably large adventure. They were later compatible with the Game Boy Color, whose color display made the games easier to distinguish visually, but the original release platform remained the Game Boy.
Pokémon Yellow followed as a revised version that placed Pikachu in the starring role. Later generations moved to newer Nintendo systems, including the Game Boy Advance, Nintendo DS, and Nintendo 3DS.