Since you mentionned BGs, let me simply say that a 20 BG stack is very uber. Just about nothing can stand against their combined charge.

If you want to exploit passive AI to its fullest, have no melee infantry. Have about 12-14 units of xbows/Venetian archers and the rest all heavy cav. Shoot them till they all die and mop up the rest with your cav (simple charge should rout the depleted units) and then have fun rout chasing.