Oh also since this was brought up earlier in the thread I thought I'd answer it. There is a way to ally with the computer vs other computers but it doesn't work that great. You almost have to make a special map that would work for it. Anyway though to make a computer an ally make them rescue(ACTIVE) in map editor, make sure its active not passive. The computer will then build and fight like your ally(with no vision though), UNTIL YOU TOUCH THEM. Once you touch them you will control all their units, so making a map where they are separated from you by water or something is the best way to do this.