I've never playing with HA factions but soon will.

However to deal with tough Phalangites with non-phalanx units the one facing them should be in HOLD. That way they last longer and the once behind should do the killing. Once the Phalanx turns then switch the HOLD.

With Cavarly charge them from behind.

Oh and with HA, slinger, and archers try to shoot them in the back or on the right side. The Phalangites have most of thier defence point in the front and right. This is done to simulate the Phalanx weakness in rear or side attacks.