I remember disliking 3 when I first saw it at the cinema.
Honestly, how is it not Mewtwo Strikes Back? You had Mewtwo vs. Mew, you had cool clone vs. original battles, you had Ash being a badass. Mewtwo was a genuinely cool character with an interesting backstory. I mean, as far as Pokemon movies go it has to be the best imo.
Then again I haven't see past Lucario & the Mystery of Mew.