Cavalry is probably the easiest enemy for an all-infantry army, have a bunch of Sarleon Halbardiers with some Sarleon MAA and let the Jatu charge right into your shieldwall...lots of dead Jatu.
If your troops are good positioned. And most importantly if you have enough of heavy troops to take massive charge of lancers even weakened by shooters. And have enough patience to stand and trying to shoot down the last horse archers...
Generally as a footmen army you are limited to standing, shooting and thinking about good positioning all the time. Too much Total War for me
And your character levels much slower.
Though I have fun in much earlier PoP version playing as Empire, they were more depended on foot and throwing weapons than now, so role playing a legionary was cool, first line action all the time, I might try it again, but for fun and role play, because it require a steady flow of new recruits..... heh
That's why I had a bunch of horse shooters(motly companions, so less recruiting for this most exposed unit), they're great for luring and drawing away charging cavalry to the right from your perspective, so they show their right, not shielded side, and your first line is quite safe from charge damage. But... thats so much tactics and time. Why not using massive heavy horse archers/lancers army to hit-and-run or blitz everyone with some heavy shooters+halberdiers regiment just for fire support.
I see this "medieval" warfare in PoP as scaled down battles from much newer times. So: the longer distance the better, and speed is equally important as armor. That's why Hero Adventurers are ultimate killing machines, if mounted knights are tanks, they're like helicopters.
BTW these new Pendor Black Archers are a very very bad guys, devastating.