i got my K1 GBA and decided to test multiplayer games. here is my findings: GAMECUBE - Does Not Work tried actual Disc's on an unmodded Gamecube, nintendo brand link adapter. tried Zelda four swords, nintendo puzzle collection, Pac-Man VS., Kururin Paradise. i even tried running Zelda Controller multiboot as a GBA Rom. however, i Did Not try Bonus Content Download, (Fire Emblem, Pokemon, etc.) my guess is the K1 team rewired the GC Link pins for TV-Out or something. GBA to GBA Link Cable - Works PERFECTY! All Games Supported. you can link with: K-Card Rom to Real Cartridge -YES K-Card Rom to Flashcart --------YES K1 with Real Cart to Flashcart -YES K1 with Flashcart to Real Cart -YES Single Card Download ----------YES K-Card Rom Download to GBA -YES Flashcart Rom Download to K1 -YES the Classic Nes series dident work on my K1 patched or not, but i tried a Real Pacman Cartridge on K1 and it worked fine. Official Nintendo WIRELESS link adapter- Does NOT Work BUT Third-Party Majesco Wireless link - Works, but only if the K1 acts as HOST. ------- Also, my Headphone adapter dident work on my K1, because it activated the pins for TV-Out, thus Blacking out the screen.