Hey everyone. first post here in this section:)
Now, about roman armies:

Praetorian army (led by a praetor acompanied by his tribune) early legion (4th century BC~early 3rd century BC):

Core troops (roman troops):
2 x Generals
1 x Hastati
1 x Principes
1 x Triarii
1 x Rorarii
1 x Accenci

Auxiliary troops (now this depends on the region as you know so I'll tell the unit type to fit in):

1 x skirmisher
1 or 2 x swordsman
1 x spearmen

if you opt to go for a 2 x swordsman don't use a spearmen I usually (when I'm trying to play historically) go for one each as it gives more flexibility...

The composition in battle should be Hastati with auxilia swordsman and skirmisher in front, 2nd line principes, 3rd line Triarii and rorarii and accensi.

This is for a standard praetorian army 8400 ~9000 men.

You can opt to make variations on this and add a cavalry unit (roman or otherwise) instead of the second general or even add artilery instead of the second general.

THen, you'd have outsized praetorian armies wich should go like this:

Core troops:
2 x Generals
2 x Hastati
2 x Principes
1 x Triarii
2 x Rorarii
1 x Accenci

Auxiliary troops:

2 x skirmisher
1 or 2 x swordsman
1 x spearmen

In real numbers this would go to 12~13K of men
On the batlefield just as the previous one hpowever you have more troops.
This armies are exceptions tough and should only be used to stop let's see, Carthage invasions or Epirote huge armies and no consul near...

then, You'd have Consular armies, led by a consul rank general.
This armies are larger and better equiped.
Here's the composition:

Core troops:
2 x Generals
2 x Hastati
2 x Principes
2 x Triarii
2 x Rorarii
1 x Accenci

Auxiliary troops:
2 x skirmisher
2 or 3 x swordsman
1 or 2 x spearmen
1 x auxiliary cavalry

Again variations are in order like removing the second general (military tribune) and adding artilery, extra cavalry, etc...

then, you have the outsized Consular army:
Core troops:
2 x Generals
3 x Hastati
3 x Principes
2 x Triarii
2 x Rorarii
1 x Accenci

Auxiliary troops:
3 x skirmisher
2 or 3 x swordsman
1 or 2 x spearmen
1 x auxiliary cavalry

This one actually should have two more units but, game limitations are a Bi...

So, here you go. Early Camillian reforms all done.
Also, Seljucids armies should include both hetaroi and katraphacts as they used both in diferent fashions (they didn't know how to take full advantage over katrapacts.

Cheers...