The problems are bigger than it sounds at first. Remember that the main problem you have with any sort of multiplayer game over the internet is synchronization -- dealing with all the various delays between communcations in order to ensure that everyone sees the same things.
A game like Jump Superstars is designed with this latency in mind. Your emulated version of Street Fighter is not; it's designed with the assumption that if one player presses a button, it will always, without exception, receive and be able to display the results of that button press to all players within a few milliseconds. That isn't the case when playing over wifi, and there is only so much an emulator can do to account for this.