Make your choice
How many people are implicit within this formation? For example, a Roman legion is 6000 men manpower plus, for example, 2000 in a supply chain.
What equipment does this formation use? Which part of the formation uses which equipment? This may include tools for siege engineers, medical equipment for healers, survival equipment for soldiers and cooking pans for the mess staff.
Which weaponry does the formation carry or is able to equip? Formations may have weapons used occasionally, in certain circumstances, or as a last resort.
Which vehicles does the formation use, and how many? Who uses the vehicles and for what? For example, the officer might have a horse, the siege weapon might have a cart, or a armoured battalion might have (in addition to 500 tanks) 20 fast-moving scout vehicles.
What is the command structure of the unit? How many of each? For example, how many cohorts in a legion, how many squads in a battalion? Are there any special HQ units, like communications support, logistics, etc?
Which tactics are commonly used by this formation? How does it gain advantage over other formations, and in which circumstances. For example, the legionnaire's testudo (turtle), a shield wall, gaining higher ground, blitzkrieg, controlling the skies or similar.
What maintenance training is necessary for this formation? What training must members undergo to join this formation?