|Hands down my favorite|
Traditional doubles formation has one player starting at the baseline on their half of the court (ad or deuce), either serving or receiving serve. Their partner is closer to the net on the other half of the court. So if the server is on deuce side, server's partner is on ad side closer to net and vice versa. Receiver's partner is usually around the service line helping call the serve and ready to react to opponent's net player.
In Australian doubles, player are still on their half of the court (ad or deuce) but shade closer to the middle line. So for example if the server is serving from deuce, they are closer to the hash mark than the singles sideline. Their partner is still up at the net but is closer to the middle of the court on the ad side.
In Monster Doubles, the net player is straddling the line down the middle of the court when their partner is serving. The idea is to cause confusion for the opponents and work on poaching skills. Imperative the net player signal their serving partner EVERY point, letting them know which way they will be moving. This helps the server know which half of the court to cover more quickly. So part of the fun of this game is to let them come up with their own super secret hand signals.
Note: traditionally hand signals are given by the net player to their serving partner with their free hand behind their back. Also, traditionally the server gives a verbal signal to let their partner know they have seen and understood the signal without the net player having to turn around and confirm.