N64 Transfer Pak

The Transfer Pak is a device for the Nintendo 64 that allows data transfer between the N64 game and a Game Boy or Game Boy Color cartridge. The Transfer Pak has a Game Boy Color slot, and a part that fits into the expansion port of the Nintendo 64 controller. This was included with Pokémon Stadium, and was used to transfer the player's Pokémon teams from the Game Boy games (Red, Blue, and Yellow) to Pokémon Stadium. This was the first time that your favorite Pokémon could be seen in full 3-D. This trend continued, with Gold/Silver/Crystal being able to hook up to Pokémon Stadium 2.

It should be noted that of all the compatible games, only two of them will give benefits to the Game Boy or Game Boy Color game, but rather just the Nintendo 64 game. For example, while you can transfer your characters from the GBC version of Mario Tennis over to the Nintendo 64 version, you can't transfer the N64 version's characters over to the GBC version. The exception are Pokémon Stadium and Pokémon Stadium 2 which allow for the modification of the player's team. Pokémon Stadium also unlocked a minigame in Pokémon Yellow.

List of compatible games

Nintendo 64 game Game Boy/GBC game Benefits
Choro Q 64 2: Hachamecha Grand Prix Race Choro Q Hyper Customizable GB Unknown
Jikkyo Powerful Pro Yakyu 2000 Powerful Pro Kun Pocket Unknown
Mario Artist Game Boy Camera Transfer images you've taken with the Game Boy Camera over to Mario Artist to edit them on a console.
Mario Golf (N64) Mario Golf (GBC) All of the characters from the Game Boy Color version can be transferred over to the Nintendo 64 version of the game.
Mario Tennis (N64) Mario Tennis (GBC) Similar to Mario Golf, all of the characters from the Game Boy Color version can be transferred over to the Nintendo 64 version of the game. Can also unlock six additional courts in the console version and four additional characters and minigames in the portable version.
Mickey's Speedway USA Mickey's Speedway USA Uploading your Game Boy Color data to the Nintendo 64 data will unlock Huey as a playable character.
Nushi Tsuri 64: Shiokaze ni Notte Kawa no Nushi Tsuri 4 Unknown
PD Ultraman Battle Collection 64 Any video game Inserting any Game Boy or Game Boy Color video game into the Transfer Pak will allow you to create your own character in the Nintendo 64 title.
Perfect Dark Perfect Dark Gives you various special weapons including the Cloaking Device, Hurricane Fists, R-Tracker, and a cheat code that will unlock all of the game's guns.
Pokémon Stadium Pokémon Red, Blue, and Yellow Battle your Pokémon from the GB games on Pokémon Stadium, unlock rewards for the GB games and play the GB games on TV via a Super Gameboy emulator.
Pokémon Stadium 2 All main Pokémon games on the Game Boy and Game Boy Color Same as Pokémon Stadium, though the amount of available Game Boy games has increased to include the second generation titles.
Puyo Puyo 'N Party Pocket Puyo Puyo SUN Unknown
Robot Ponkottsu 64: Nanatsu no Umi no Caramel Robopon Sun, Star, and Moon Versions Unknown
Super B-Daman: Battle Phoenix 64 Super B-Daman: Fighting Phoenix Unknown
Super Robot Taisen 64 Super Robot Taisen Link Battler Unlock new units to use in the Nintendo 64 version.
Transformers Beast Wars Metals 64 Kettō Transformers Beast Wars: Beast Senshi Saikyō Ketteisen Unlock Megatron X in the N64 game. As there is no save feature, the cartridge must be inserted to play as Megatron X.