I'm jealous. The only thing the AI does in my battles (on Hard) is form two lines, and charge me head on - regardless of terrain, attacker/defender status, army size etc. I had a battle as Pontus against Media - they had a line of slingers and a line of spearmen, and a general's bodyguard unit - and the infantry + general simply charged my phalanx/hoplite line head on lol, while raining stones with their slingers...which were decimated by my flanking cavalry (they took no notice of that, of course).