I guess he means HAMACHI/visualboy advance link.
Hamachi it's a virtual network manager, used to create virtual networks to play multiplayer mode in the internet like if u were in a network, to avoid registration, autentification...
VisualBoy Advance Link it's a mod of the GBA emulator VisualBoy Advance, in witch u can play via network.
so he means to create a virtual network in the internet via hamachi, and play using the emulator in that network.
but this is useless, cause it's much easier to battle in the internet using Pokemon Netbattle