Well, to be fair, I'm not a fanfic mod - just a mod who likes writing fanfics. =P So I can't 'approve' anything...
But I do know that any sort of stories are fine, as long as they are properly written (no straight-out scripts, proper grammar, no excessive gore and the such, at least 3 pages per chapter (if not so for the last two, fanfic mods are the ones to check with then), etc, etc), and if it's a non-Pokemon story (like Brawl - it has Pokemon admittedly but it's separate enough, I feel, and is a different fandom althogether anyway), then it's to go in the Non-Pokemon fanfic section rather than the main fanfic section.
(Continued below - darn character limits!)