Transfer Pak

The Transfer Pak is an accessory for the Nintendo 64 controller. It features a cartridge slot compatible with Game Boy or Game Boy Color games. When plugged into the controller's expansion port, it allows for the transfer of data between supported N64 and GBC games to access additional content. The Pokémon Stadium games, with which the Transfer Pak was initially bundled for sale, also feature the ability to emulate specific Game Boy Pokémon games on the N64.
The Transfer Pak was supported by twenty N64 and 64DD games released between 1998 and 2000, only six of which supported it outside of Japan. Several games which initially planned to utilize the accessory were either cancelled or had the functionality removed. A similar accessory for the 64DD, the was also never released. As a result, the Transfer Pak is recognized as one of the first examples of connectivity between Nintendo's home consoles and handhelds, but retrospective coverage of the accessory has found it largely unnecessary.

Overview

The Transfer Pak was developed by Nintendo Research & Development 3, and was first revealed at Nintendo's Space World 1997 trade show. It was released in Japan as a pack-in with the game Pocket Monsters Stadium, which required the Transfer Pak for many of its features. In North America and Europe, the Transfer Pak was similarly bundled with Pokémon Stadium for its English-language release in 2000, receiving a standalone release shortly thereafter. While the device itself is physically compatible with all Game Boy and GBC Game Paks, N64 games can only connect to games from the same region.
Unlike the Super Game Boy peripheral, which allowed Game Boy games to be played on the Super Nintendo Entertainment System, the Transfer Pak's primary use is not to play Game Boy games on the N64. Nintendo and Intelligent Systems developed a separate accessory to serve this function, the Wide-Boy64, but it was not released to the public and was instead only available to game developers and members of the gaming press. However, the Pokémon Stadium games include a built-in Game Boy emulator, allowing users to play compatible Pokémon games on the N64 by inserting them into the Transfer Pak. The emulation software is based on the Super Game Boy, including applying the same borders and color palettes during gameplay.

64 GB Cable

The 64 GB Cable was a similar but unreleased accessory, designed by Nintendo subsidiary Marigul Management for use with the N64's 64DD peripheral. The cable would have connected from an N64 controller port to a proprietary port built directly into compatible GBC cartridges, to transfer data between the GBC and a 64DD storage disk, and to use the GBC as a sub-screen for certain 64DD games. This was demonstrated at Space World 1999 with the game DT Bloodmasters, a trading card game directed by Masanobu Endō that was planned to use the 64 GB Cable to exchange cards between the two systems, and allow players to privately view their cards on the GBC screen. The cable and DT Bloodmasters were ultimately never released due to the 64DD's underperformance, though its GBC counterpart, DT: Lords of Genomes, was released in May 2001. Derby Stallion 64 was also intended to support the 64 GB Cable, using the GBC as a second screen to place private bets on horse races, but this feature was removed after the accessory's cancellation.

Supported games

The following is a complete list of all 20 Nintendo 64 and 64DD games that are compatible with the Transfer Pak, along with the corresponding Game Boy and Game Boy Color games. Some N64 games' Transfer Pak functions are only available in certain regional releases, due to their GBC companion games not being released in other markets.

Nintendo 64 game	Game Boy game	Features
Choro Q 64 2: Hachamecha Grand Prix Race	Choro Q Hyper Customable GB	Each player's maximum speed is increased in Hachamecha Grand Prix Race if their controller is connected to Hyper Customable GB.
Jikkyō Powerful Pro Yakyū 6	Power Pro Kun Pocket	Baseball players can be transferred from GBC to N64; a password can also be used in place of the Transfer Pak.
Jikkyō Powerful Pro Yakyū 2000	Power Pro Kun Pocket 2	Baseball players can be transferred from GBC to N64; a password can also be used in place of the Transfer Pak.
Mario Artist: Paint Studio	Game Boy Camera	Players can take photographs using the Game Boy Camera and import them for use in the game's creation suite.
Mario Artist: Talent Studio	Game Boy Camera	Players can take photographs using the Game Boy Camera and import them for use in the game's creation suite.
Mario Golf	Mario Golf	The player characters from the GBC version's story mode can be temporarily transferred to the N64, allowing them to gain experience points through gameplay that will be transferred back to the GBC version. The GBC version also allows players to view their high scores from the N64 game.
Mario Tennis	Mario Tennis	The player characters from the GBC version's Mario Tour mode can be temporarily transferred to the N64, allowing them to gain experience points through gameplay that will be transferred back to the GBC version. When the two versions are connected, Yoshi, Wario, Waluigi and Bowser are unlocked as playable characters in the GBC game, along with their respective minigames. Connecting both versions again after completing these minigames will unlock additional tennis courts in the N64 game.
Mickey's Speedway USA	Mickey's Speedway USA	Connecting the two versions is the only way to unlock Huey as a playable character in the English N64 release. In the Japanese release, Huey is unlocked through normal gameplay.
Nushi Tsuri 64	Umi no Nushi Tsuri 2	Players can transfer data from their in-game notebooks on GBC to N64. Sea fish that are normally only present in Umi no Nushi Tsuri 2 can also be added to the fishing pond in Nushi Tsuri 64
Nushi Tsuri 64: Shiokaze Ninotte	Kawa no Nushi Tsuri 4	Players can transfer data from their in-game notebooks on GBC to N64.
PD Ultraman Battle Collection 64	Any	Players will unlock different characters for play based on which Game Boy game is inserted, similar to the use of CDs in Monster Rancher.
Perfect Dark	Perfect Dark	Connecting the two games immediately unlocks four cheats in the English N64 release—Cloaking Device, Hurricane Fists, R-Tracker, and All Guns—which would normally require players to complete several difficult in-game objectives to unlock them. The game also originally featured a mode called "Perfect Head", through which players could transfer photos from the Game Boy Camera to create characters with real-life faces for use in multiplayer matches, but this mode was removed during development, as a result of both technical issues and a wave of anti-violent video game sentiment after the Columbine High School massacre.
Pocket Monsters Stadium	Pocket Monsters Red, Green, Blue, and Yellow versions	By connecting to a Game Boy Pokémon game, players can view and organize their Pokémon, transfer them from the Game Boy games to Stadium for storage and use in battle, or emulate the Game Boy games for play on their television, the speed of which can be doubled or tripled through unlockable settings. Players can also teach a transferred Pikachu the "Surf" ability in Stadium, which can be used to unlock a secret minigame in Yellow.
Pokémon Stadium	Pokémon Red, Green, Blue, and Yellow versions	In addition to retaining all the Transfer Pak features from the previous game, players can unlock special prize Pokémon to send to the Game Boy game.
Pokémon Stadium 2	Pokémon Red, Green, Blue, Yellow, Gold, Silver, and Crystal versions	In addition to the Pokémon transfer and emulation functions from the previous games, Stadium 2 allows players to transfer items, play as transferred Pokémon in its minigames, view and customize the player character's room from Gold, Silver, and Crystal in 3D, and receive special items in Gold, Silver, and Crystal using the "Mystery Gift" option. The Japanese version could also connect to Crystal to watch prerecorded battles downloaded from the "Mobile System GB" networking service prior to its shutdown in 2002.
Puyo Puyo~n Party	Pocket Puyo Puyo Sun	Players can view a gallery in Party of special illustrations earned in Sun, some of which can only be unlocked by connecting the two games.
Robot Ponkottsu 64: Nanatsu no Umi no Caramel	Any Robot Ponkottsu Sun, Star, and Moon versions	Special food items that provide different stat boosts will be generated based on which game is connected. Connecting to one of the Robopon GBC games will also allow players to exchange and battle Robopon characters between GBC and N64.
Super B-Daman: Battle Phoenix 64	Super B-Daman: Fighting Phoenix	Items can be transferred from Fighting Phoenix to Battle Phoenix 64.
Super Robot Taisen 64	Super Robot Taisen: Link Battler	Players can transfer character experience between games, as well as unlock playable units in each game that are otherwise exclusive to the other. Players who link the two games can unlock up to 4 additional units in 64, and up to 21 additional units in Link Battler. A set of maps featuring the four additional units will also be unlocked in 64.
Transformers: Beast Wars Metals 64	Any Kettō Transformers Beast Wars: Beast Senshi Saikyō Ketteisen	In the Japanese version, the player's default health and energy capacity can be positively or negatively affected based on the connected game. Kettō Beast Wars grants the greatest possible boost, and unlocks the secret boss Megatron X as a playable character.