Okay,
1. Read the rules on the first post, it clearly states the intention of this thread is for current pokemon media, being the games, anime, manga, or any other officially licensed merchandise
2. As a thread on the Orange Islands board, it is subject to the rules of the the Orange Islands board as well, which clearly state the intention of this board is for current/upcoming pokemon media, being the games, anime, manga, or any other officially licensed merchandise.
Now, if you want to use a fanfic to explain a theory of an existing pokemon media (like using a Nuzlocke comic to explain how Gary lost his Raticate in the Kanto games) then you may do so, because you are using a theory to explain an in-game mystery (so the focus is on the game, not the fanfic). Just as long as your non-canon explanation does not go against official canon, an exception being made for the pokedex entries because they already make no sense.
But asking "Why aren't these Creepypastas marked not true" is not a pokemon mystery, or even a mystery at all. The answer is just "because the website hasn't done it." Of course they aren't true, nobody has ever died due to a haunted video game.
If you have any further questions, feel free to PM a mod like Codraroll or DH-101 and have them explain it to you. Or if you really want to discuss non-official pokemon media, then maybe ask them if you can create your own thread and where an appropriate place to put it would be.