The Canon of a series is a classification of which events actually occurred and which characters, locations, etc. actually exist within the series' fictional universe. Creators of series occasionally issue official statements as to canon, thus creating an official canon. Presently, the Super Mario series and its spin-offs do not have an official canon. Therefore, under no circumstances should any user argue that any official source does not apply because it is "non-canon." Whether a source is canon or non-canon to another source is of no importance to the articles. Since there is no canon, any assertion that a canon does exist is speculation, and therefore does not belong on the articles. However, there are hints at a continuity within the series. This concept is explored at length in MarioWiki:Chronology.
The issue at hand is that certain sources are not directly linked to the rest of the series' continuity. For example, The Super Mario Bros. Super Show! can be considered to be in a separate timeline from Super Mario Bros. or take place prior (live-action segments) and after (cartoon segments) the events of the video game. For this reason, the Super Mario Wiki wishes to clarify that in no way should its organization of articles be considered an assertion of canonicity in the Super Mario series. Rather, our organization is simply a way to convey information in the clearest manner possible.
Our goal is to cover the entire Super Mario series. Thus, it is of little to no importance whether or not a particular source is canon to another source.