I'm afraid I can't replicate that, the Randomizer works as intended after saving, quitting and then loading. It works so well in fact, it even randomized the debug add pokemon function...
Just paste the whole zip in your project, or copy contents from The zip's graphics folder to your gane graphics folder, Audio in Audio and Plugins in Plugins.
Looks like you only extracted the Plugins Folder, you have to extract all the folders in your project root (the game main folder where Graphics Data Plugins Game.rxproj Game.exe.... Etc is located) to make sure all the files are there.
This plugin adds a better Mega Evolution animation to the Essentials.
How to use:
1. Download and Extract the Zip file to Project root.
2. Recompile Plugins.
3. Enjoy.