Mithridatic Wars- Historical note

[seleucid empire]

Hello, ive noticed that during the mithridatic wars, pontus and armenia were able to call upon huge numbers of troops very quickly against Rome
Battle of Chaeronea: 120 000
Battle of Orchomenus: 80 000
Battle of Tigranocerta: 100 000

Im going to start a pontic campaign and for role playing purposes i will use fd to give Rome greece and start a war with them on 88 BC

for my campaign if an army has 3000 men then i role play that as 30 000 so i will have four stacks at chaeronea, 2-3 at orchomenus and 3 at tigranocerta
Does anyone know the compostion of these armies?? and how the pontus managed to raise such powerful armies (considering that the seleucids and ptolemies at their height could only muster 70 000)

The qualities of these armies couldnt have been as good as those of the hellenistic kingdoms could they?? but then i read that there were scythed chariots and bronze shields present in the first two battles