Get some Kern from Ireland, stand them behind your best shieldwall infantry and let the huscarls attack the shield wall. The Kerns' javelins massacre the Huscarls until they break - then your fleet of foot Kern can chase them off the battle field - see easy isn't it!! While recruiting in Ireland, pick up a few gallowglasses as well - a great unit either charging in frontally - a bit throwaway, but do a lot of damage - and even better coming in the flank or rear.
As a Pict, I would have thoght your mounted XBows would be a good counter as well.