[PVCpirate]

I think there's going to be 2 schools of thought on this, either picking for a true backup, or picking for more strategy options.

The first one will happen if the alliance captain is worried about one of the first 3 robots on the alliance breaking down, or if they just want to be safe. They'll pick a 4th robot with the same or similar capabilities as one or more of the first 3. This way, if there's a breakdown, this 4th robot can step right in, and the strategy doesn't have to change.

The other way is to pick a robot that is unique with respect to the first 3 bots on the alliance. If an alliance captain follows this line of thought, it may open the door for specialized robots like goalies, big catching targets, and others. If you have the ability to put 2, 3, or even 4 different, effective combinations of robots on the field, you can play massive head games with your opponent.