[@Rultaos] That's why most of the vehicles and stuff will likely just be "reskins" of the same unit as I call it. So people don't need to worry about if this tank's 120mm cannon can damage that vehicle's 50mm armor with reactive plates at a 60 degree angle or what have you. Its also why I'm not having it be PvP but more PvE so that people can focus on writing for character's and personal tactics over what counters what and why this maneuver would best that action.

[@neogreggory] I'm going to use what Yenn (original creator of the idea) had written down mostly:

[hider=MockZ, What are they?]
When a customer first purchases their MockZ they will receive a sealed box, that Is container freezing that which is inside. When opening it, you will find so many tubes of frozen bodies, each of them a blank gray slate to work on. Then you will also find a console in which you can completely customize every aspect of these bodies, from skin color, hair color, to sex, build etc. 

Now MockZ may be purchased from stores, and created in labs, but they are living breathing creatures, intelligent, and understanding of their own existence. When MockZ were first created, there was great debate as to whether the creation of these beings should be shut down, but money lining pockets, and promises of shares soon ended the debates and it was approved and pushed through, making MockZ one of the biggest selling products in the world, that was 10 years ago. 

When MockZ are born (defrosted, and dumped out of their tube), they appear exactly as you created them, with knowledge of language, simple math, reading, writing, and your name. The first two weeks of their life is the most important, as that is when they soak up the most information, and knowledge you teach them, SuperGen has posted hundreds of education videos online for your MockZ to watch. Unfortunately these did not include War Tutorials, in which MockZ owners must find other ways to educate their MockZ in the ways of War.
[/hider]

[hider=Building your MockZ]
Yes, it’s realized that between all the different nation choices you may not want to stick with just one. That is perfectly fine, also depending on an Aesthetic aspect you choose for your MockZ does not decide skin color, and culture. You can easily have Africans who wear German Nazi Uniforms, and have a US style Democracy. Other than that, everything is up for grabs consider the anti-aging of the MockZ and the fact that they are essentially immortal when it comes to diseases, and dying of old age, staying perpetually at whatever age you created them.

Now, even though you can mix things, it is very important you be careful about what you mix. You do not want to buy your MockZ several hundred American rifles, then buy them a bunch of Russian Rifles, the learning of different weapons can be hard in a military environment, and makes it difficult for your MockZ to train. The same can be said of vehicles, etc. 
[/hider]

Its going to be very similar except that there are plenty of videos online on how to train MockZ and even sort of MockZ "boot camps". Think like how there are videos on how to train your dog and doggy camps and such. Plenty of people in universe even have MockZ who they just use as like glorified ant farms and watch as they build cities and such in their backyard or living room. I will also say that they can repopulate themselves but have gestation times of at least half a year with only special types of MockZ that are fertile and invetiably cost much more. 

tl;dr - humans only, they can learn other skills besides war and can grow their own personalities beyond what you first make for them, customization is from you being able to alter how they physically look and their clothing, they can form relationships and they can die from battle.

That last bit is actually going to be a corner stone of my own Division. Originally they were two divisions owned by two brothers but after a series of devastating and crushing losses, they have been combined into a single Division with limited resources and quality units.