Are there any Gameboy Advance Emulators that can simulate linking, that way two computers running the emulator can link with each other over an Internet connection?
If one does support this feature, is it limited to which games it supports linking?
Using VBA (I use version 1.8.0) and want to link offline (using the same PC), go to: Options > Emulator and deactivate the option "Pause when inactive window". then go to: Options > Link and activate the "Wireless Adapter".
Now open two VBA, configure joypad 1 for both of them (using different buttons on each), load the game on both, and have fun!
If you want to play in LAN (two PC without internet), but you can try to configure the Link options to the "network" option and start the server, then on the other pc, try to connect on the IP address and port that the server PC is configured.