In literally every sci-fi I've ever seen where there were prisoners involved, they were used against their will for any number of things...
...so why not be forced into competing in the Tournament?
Team Colors are largely on the back and the sides of the legs.
What's being used for the Talk Texture I was originally planning on putting on the front, but decided against it.
Enjoy!
https://www.mediafire.com/file/hvd9hjzyqg7t6cu/SoldierSkinsVillains.zip