Not sure if this helps any but I remember Battletoads being a three player game and they all shared the same coin mech and you would select the player by using the player 1,2,3 start buttons. With X-Men you would select your player by adding a coin to the corresponding coin mech (mech 1 may have been wolverine, 2 may have been cyclops, etc). Not sure how your particular cab is wired up but maybe this makes a difference. If you were to add coins to the other mechs and all the mechs are wired to one, you would only be adding coins to player 1 with the x-men wiring configuration.