Hey, sorry for the delayed response - the forced migration to the new Discussions module hasn't been displaying notifications in the same way as the Forums.
The majority of existing guidelines are on the main page. We really haven't had any major issues apart from that, but we do have a quick and dirty content policy page and [deletion policy (linked below). The main issues fall under copyright (including crossover) and being generally appropriate for the target audience of Huntik.
Here are a few other points from the original forums.
http://huntik-fanon.wikia.com/d/p/1882963356680352180 • Mainly deals with why we don't use crossover.
http://huntik-fanon.wikia.com/d/p/2124695121952928182 • Includes some Huntik conventions we try to keep. • Details abandoned pages (those created with just an infobox and no content). • Details requirements of image licensing / copyright.