Actually, IIRC, No$GBA was the first emulator to have GBA (!) multiplayer. Assume the worst, hope for the best and you won't be disappointed...aparently the author of No$ is on hiatus, and as far as I can see all others pale in comparason, whoever made VBA figured how to add a link function for gba games though
Visualboy Advancelink was the first to have multiplayer accessActually, IIRC, No$GBA was the first emulator to have GBA (!) multiplayer. Assume the worst, hope for the best and you won't be disappointed...