Nah, nothing wrong with the stock Pezhetairoi. The Klerochoi Agemata, the 120-man super phalanx, might be a little overpowered.

I haven't had much issue with the Galatian Kleruchoi. Sure, they're tough, but they break and flee like any other unit. Just keep the flanks of your phalanxes covered, and you should be fine.