MarioWiki:Canonicity
As with all fictional universes, the Marioverse has a set of canon, or levels of official material. The Super Mario Wiki attempts to create the most accurate articles possible, and will turn to different official materials to help understand conflicting issues. Video games are of the highest canon, especially video games published by Nintendo (usually with the Official Nintendo Seal, as opposed to Mario's Time Machine and Hotel Mario). Both remakes and the original versions have the same level of canon - they are simply alternate versions of the same game. The events depicted in the games take precedent over other official material. This includes instruction manuals, which often have story elements not depicted in the game itself, and official player's guides from Nintendo. Instruction manuals take precedent over player's guides, as manuals are specifically packaged with the game.
Any information that is made up by fans (including fan-made stories and video games) are considered non-canonical. Beta Elements are also non-canonical, as they were not released in the final version of the game.
Comics, cartoons, and movies are considered alternate-canon. They are not official in the realm of video games, but have their own canon. The information is still canonical, but only in that specific medium (not the video game universe).