What cable lets players trade Pokémon between the original Game Boy games?

The Game Link Cable lets players trade Pokémon between the original Game Boy games.

Pokémon Red and Blue used the cable to connect two Game Boy systems. The connection allowed players to trade Pokémon and battle one another, making communication between players a central part of completing the Pokédex.

Trading was not merely an optional extra. Certain Pokémon were exclusive to one version, and some species could evolve only after being traded. As a result, owning a single game did not provide every practical path to the original 151 Pokémon.

The cable is sometimes confused with Nintendo's Transfer Pak, which connected a Game Boy cartridge to a Nintendo 64 game such as Pokémon Stadium. That accessory served a different purpose. The Game Link Cable directly connected compatible Game Boy systems for multiplayer features.