The teams decide between each other what number of people will be participating e.g: 3v3 or 4v2
In a 3v3 the war will probably go like this:
P1A VS P2A
P1B VS P2B
P1C VS P2C
each battle will consist of what even the two teams agree on.
Who ever has the most wins, win the war. If their is a draw of some kind then put a draw in your teams WAR record, no tie-breakers.
That is just the rules briefly. However it is all down to what the two teams agree on.