Board Thread:General Discussion/@comment-25523075-20150812171427/@comment-3328029-20150812220046

mw.config.get("wgAvailableSkins");

Just go to the javascript console for the wiki and enter that. should return an array of all skins. source: mw:Manual:Interface/JavaScript

Edit: This is in response to your original question; I personally have no knowledge of any uses on wikia besides monobook, oasis, and wikiamobile.