in all of the quake games they have an option to make your enemy's full model one color. (usually bright green)
I mean random characters.
Let's say for example a player wants their model to have a Slenderman skin. When they're playing team games like CTF, a team colored vest (and maybe a helmet) will be placed over the model so that the player with the Slenderman skin can't hide in shadows but can use their vest (and maybe their helmet) as camouflage so they can crouch in front of barrels and not be seen to easily.
In DM, the vest (and helmet, provided that it's added) will be removed from the model so that the player can fully show off their cool Slenderman skin.