Exactly, play a random map against three allied AI opponents, on normal difficulty. For example, in Heroes of Might and Magic III, it's not even challenging!
To be honest, when playing against three allied AI opponents on a random map... I couldn't win... But that was only in the first 5-6 attempts... Then I started to get the hang of it and played better...
For those who think the AI is too weak... play solo against several AI opponents who are allied...