How to install mods for WWE Battlegrounds:

Download a mod. It should be ".pak" format. An example file name would be "JohnCena-Purple.pak"

Navigate to your WWE 2K Battlegrounds game folder.

Look for the folder "Content", and then inside that one, "Paks". You should see WWEPlaygrounds-WindowsNoEditor.pak

Create a new folder called "~mods" (tilde included for alphabetical load order)

Drop your mod pak inside this folder and launch the game. That's all there is to it! Enjoy. 

Video coming soon