Hm. I know that each movie belongs to a season but I think it's hard to tell between which episodes they take place. I never saw a movie as non-canon but I did realize that there are some antagonisms between the movies and the TV show - for example when Ash and friends meet Lugia in season 5 and don't seem to recognize it. Also what Ash and Co. go through in the movies should have an effect on their personalities and their further actions but it doesn't seem to have any.
If all movies are canon, I think only the Pokemon in the movie can give us a hint to when the movie takes place, e.g.:
movie 2: after Tracy catches Scyther and after Charizard starts to obey Ash, before they reach Pummelo
movie 3: Ash already has Totodile so it must be somewhen after the episode "The Totodile duell"
movie 4: I think Ash sent out Bayleef, so it must be somewhen after "Turning over a new Bayleef"
movie 10: after Dawn catches Buizel