Pantodapoi are not particularly reliable soldiers, but they can give a good account of themselves in battle if deployed and supported properly. They wear no armour, and have only a light shield for protection allowing them to fend off light cavalry and missiles for a short time.
The most basic and numerous of the infantry units used by the non-European Successor States were the Pantodapoi infantry. These men were called from a variety of nationalities and were usually settled in certain areas for garrison duties and the like. There were Jews, Syrians, Cilicians, Persians, Assyrians, Native Egyptians, and many other peoples counted among their number. They are not particularly reliable soldiers, but they are certainly better than their eastern counterparts. They can give a good account of themselves in battle if deployed properly. They wear no armor, and have only a light shield for protection, so most other infantry will slaughter them in droves. They can fend off light cavalry for a time, if need be.
Historically, the Pantodapoi were a group of various nationalities that were used as a militia levy and defensive group for towns and villages prone to raiding. While the name is conceptual (meaning, from everywhere), they were a standard fighting force of the day. They were trained rudimentarily, but had enough training to be counted as superior to many militia levies. They had some experience fighting off nomadic raiders, so they can be useful against light troops and some light cavalry.
These levy spearmen have been recruited from a local populace under the control of one of the Diadochoi. Carrying a spear and shield, their equipment is minimal. Their morale is not great to say the least. Their training is practically non-existent. Of their devotion to duty, the less said the better. Conscripted in a pinch, not much can be said in favour of pantodapoi other than having them on the field when nothing else is available is better than not having them... maybe.
The Successor states generally avoided arming the various peoples under their hegemony. It did happen, but mostly as light missile and skirmishing infantry. In the event of conscription into other forms of infantry, the consequences could be very troublesome as seen by the constant uprisings the Ptolemaic kingdom faced in the decades around the turn of the 2nd century. Regardless, in dire situations of crisis, most kings would take the risk and the pantodapoi (a conceptual name meaning 'from everywhere') are an example of this. These infantrymen could be raised from any population from anywhere, given a spear and shield, and ordered to hold the line where there were gaps in recruitment. It is doubtful that much was ever expected of infantry recruited in this way, but to many commanders it was better than nothing.
The Pantodapoi are a cheap unit to be used as garrison unit or to fill the ranks of an army. They can hold the line if used properly and with a general nearby but arrows and javelins will see alot of their numbers dead and they cannot be expected to hold for long against heavy infantry or a phalanx unit.