[Blade Raider]

Depends on the show, depends on the writer and/or showrunner, depends on the movie/special/whatever, but most of all it depends which fan you ask. At the end of the day, it's a mess with no real answers and Toei sure doesn't care.

For me, it's all canon and it's just a matter of sorting it all out on a case by case scenario. Worst case scenarios are that a movie/special becomes an alternate timeline, alternate universe, or it was just a case of plain old bad writing.

I will say there are some movies/specials that are absolutely canon and pretty much no sane person will argue with you on it. Examples include (but not limited to) Den-O, W, and Ex-Aid. All of these have major plot points in the movies and the shows reference the events of the movies before and/or after. Even then they don't always fit perfectly.