What accessory connected two Game Boy systems for Pokémon trading and battles?

The Game Link Cable connected two Game Boy systems for Pokémon trading and battles.

Pokémon Red, Green, Blue, and Yellow used the Game Boy accessory to let players connect two handheld consoles. With the cable, players could trade Pokémon and battle one another, turning the games’ collecting systems into a social experience.

Trading was especially important because each paired version contained Pokémon unavailable in the other version. A player who wanted to complete the original Pokédex therefore needed access to another compatible game and a connection method. The cable made that exchange possible before wireless communication became common in games.

The Game Link Cable is sometimes confused with Nintendo’s Transfer Pak, which connected certain Game Boy cartridges to Nintendo 64 games. It is also different from the Super Game Boy, an adapter that played Game Boy cartridges on a television through the Super Nintendo. In early Pokémon, the cable was the key tool for multiplayer interaction.