NO$GBA 2.6a, has a problem with GBA roms and doesn't play them as good as VisualBoy Advance when it comes to going through fog in Pokemon. The only emulator, NO$GBA, is able to connect GBA to GBA.
In VisualBoy Advance 1.8.0 beta3 they took out the feature of linking because they figure out like everyone else that the linking feature doesn't work.
I don't think VisualBoy Advance has the ability to connect like NO$GBA does and NO$GBA could only allow you to connect to yourself.