The hoplite is the classical example of heavy infantry; I doubt anyone is going to disagree with that. However, warriors (I avoid the term soldiers, because it implies a salary) typically had to provide their own armaments. Most were young and not rich, they had shields but often lacked body armour. Greaves were uncommon too. Only the oldest and wealthiest actually had the stereotypical, very expensive, bronze muscle cuirass.
You see the same in the early Roman Republican ("Polybian") army, with the hastati, principes, and triarii.
Likewise, it's highly unlikely all phalangites would have the same body armour. Many different types of armour were used in the Macedonian army. Alexander's hypaspists were the elite, they could afford the classical muscle armour; I'm not saying all of them always wore one, but it's certainly possible they normally fought as traditional hoplites.
Finally, 0 A.D. is a game, and has to generalize some things. Alexander's cavalry sometimes fought on foot, and pezhetairoi (ordinary phalangites) occassionally fought with javelins instead of in a pike formation. I think it's both unnecessary and undesirable to try to implement this.