User blog comment:KidVegeta/Canonicity/@comment-2063411-20101008163207/@comment-3097771-20101008201855

Movie-wise, I don't think Toriyuma wrote any of them, besides being heavily involved in the Cooler design. The reason why some of them are canon, is because they don't break the story in any way. They could have taken place without DB or DBZ being effected at all. The movies which I have listed as non-canon, such as the Turles movie, have been listed so because they do negatively effect the DBZ story. GT, being not written by Toriyuma is in the same boat as the movies. If it doesn't destroy the canon, then it's fine. Unfortunately, it does, so I had to list it as non canon.