Since I'm using actionscript (main part of the language), I would need at least two scripts. One would handle the server script while the other three handles the client (the game code basically).
I would also need a server to hold the server script (probably use whirl or something similar).
All I would need to record for the server is the scores of the players, the lives of both players, and location on the x,y grid of both players. With the player location I can relay to the players where their opponent is (in a soft transparent so it doesn't obstruct their view) and allow them to see how they are doing.