It's Pony Wiki:Fanon Policy

Fanon Policy All rules listed on the Regulations also apply to fanon content. Fan content is allowed on the wiki, but should not be placed on articles. Fan fictions are only to be made in blog posts. Remember to include the category "Fanfiction", on the blog post. If you wish to discuss fan content, it should only be done on message walls, blog posts, or Discussions. Fanart is only permitted on blogs, userpages, and wall posts. No inappropriate fanart. We do not allow nude fanart, or any sexual content.