So.. i had the same problem, i wanted to link my pokemon firered game on gameboid with my friend, we both have android.. as far as i've seem, it's possible today to do something like that directly.. but,
i've copied both files (mine and my friend's) to my notebook, opened with visual boy advanced which can link and done
in case of pokemon trading, after all proceeds on notebook, obviously you have to copy save files to android.
note: on the emulator i'm using, save files must have their extension renamed from .sav to .sa1 ans .sa2
that's not as portable as if we could just link by bluetooth or something anywhere we are, but that's not that impossible you're all saying, to trade pokémon or battle with your friend..
hope i have helped. :D