I found this crazy link cable setup on Wikipedia: use two GBA cables to link GB/GBC games. : r/Gameboy
Hispeedido 2 Player Game Link Cable Connect Cord Lead For Nintendo Gameboy Advance Gba Sp Gbc Link Cable - Accessories - AliExpress
Amazon.com: GBC Link Cable, 3.9Feet 2 Player Link Cable Connect Cord for Nintendo Gameboy Color/Pocket/Light, UIInosoo : Video Games
Hispeedido 2 Player Game Link Cable Connect Cord Lead For Nintendo Gameboy Advance Gba Sp Gbc Link Cable - Accessories - AliExpress
Amazon.com: Link Cable for Game Boy Color, Pocket and original Game Boy Orange : Video Games
Amazon.com: CHILDMORY 2 Player Link Cable Cable Adapter for Gameboy Color GBC : Industrial & Scientific
GB - 2 Player Link Cable For Gameboy / Color / Pocket - Brand New #111 – vandalsgaming
Can you play an Og Gameboy game with a gba link cable on two gbas? : r/Gameboy
2 Player Link Cable Connect Cord Lead Compatible For Nintendo Gameboy Advance GBA SP GBC - AliExpress
Amazon.com: Tomee 2 Player Link Cable for GBC/ GBP/ GB : Video Games
Amazon.com: GBC Link Cable, 2 Player Link Cable Connect Cord Compatible with Nintendo Gameboy Color, Game Link Cable for Gameboy Color/Pocket/Light, 3.9Ft Black : CSTESVN: Video Games
InterAct PlayLine Link Cable for Game Boy Advance and Game Boy Color - – J&L Video Games New York City
Amazon.com: TraderPlus 2 Pcs GBC Link Cable Two Player Link Connect Cable Cord for Nintendo GameBoy Color GameBoy Pocket GBC GBP GBL : Video Games
Amazon.com: GBA Link Cable, 2 Player Link Cable Connect Cord GBA Connection Line for Nintendo Gameboy Advance SP/Gameboy Advance, 3.9ft : Everything Else
Amazon.com: Mcbazel 2 Player Link Cable Connect Cord For Nintendo GBA GameBoy Advance and SP, GBA Link Cable - 3.9FT, Black : Video Games
GameCube – Game Boy Advance link cable - Wikipedia
GAME BOY TWO 2 PLAYER LINK CABLE for GAMEBOY COLOR GBC CONSOLES, ALSO FOR GBP | eBay
4-Player Game Link Cable for Game Boy Advance - Tomee - Stone Age Gamer
Amazon.com: Timorn GBA SP Link Cable GBA SP Charger Cable GBA SP Headphone Adapter USB Charging Cable 3.5MM Headphone Earphone Jack Adapter 2 Player Game Link Cable for Gameboy Advance SP :
Amazon.com: GBC Link Cable, 3.9Feet 2 Player Link Cable Connect Cord for Nintendo Gameboy Color/Pocket/Light, UIInosoo : Video Games
NINTENDO GBA / GBC 1.5M - 4 Multi Players Link Cable GameBoy Advance / Color | eBay
