From the Super Mario Wiki, the Mario encyclopedia

HotCat is a JavaScript program that helps registered users easily remove, change and add categories, originally written for Wikimedia projects. The code was copied by Super Mario Wiki contributor B.wilson from - and can be used on the Super Mario Wiki as well!

To use this script, please copy the following:

to your monobook.js or common.js.

Make sure you bypass or clear your cache, and it should be up and working!

If you have any questions, or if it does not work for any reason, please contact me at your convenience.