Two teams play a set of doubles where the serving team will always begin the point with both players at the baseline followed by transitioning to the net once the serve is in. The receiving team should begin every point in a one-up-one-back formation. 
Example (see graphic below):
Team A-B is the serving team; they begin both on the baseline. Team C-D is the receiving team and are in a one-up-one-back formation. 
As soon as A’s serve is in, A and B move up to the net. Play the point out. Keep score and once a game is over, team C-D will be the serving team beginning every point from the baseline while team A-B will switch to the one-up-one-back formation. 

Note: The game teaches the serving team to play aggressive, work together and improve the transition from the baseline to the net (split steps, low volleys, smart decision making as far as placement of low volleys etc.)