the battles against a full stack ( often more than one ) of mongols are hard ones ... their lancers charge often rout all your army and you cant reorganize cos the attacks of the light cavalry ... only good strategy for me is to weak them with green armies of crossbows/halbeards ( muck better than pikemen !for me ) ... they kill you with arrows and the lancers charge but you should be able to inflict enormous damages with crossbows and catapults ... the softened stacks can be assaulted then with elite armies ( good crossbows + very good cavalry )