Multiple AI's of varying difficulties

Is there a way to have a game where you fight multiple AIs, but of different difficulties?

For instance, 1 hard, one Moderate?

Also, some of the Hard AI's seem to be bugged in that they aren't upgrading their towers at all. May seem like a trivial issue, but when fighting a "Hard" "Conqueror" AI, I was easily able to just run him over completely due to his total lack of defensive buildings. Sure, I could play a "Protector" or "Defender", but those guys just wall like crazy, instead of producing a sizeable army.