I surprisingly say that the Charizard of this episode isn't Ash's Charizard. Why?
-Because the summary didn't say a word about Charizard. Only the title references Charizard at all.
-Because the past three times that Ash's Charizard returned, before his apparenace another Charizard appeared on-screen having a relatively big role.
-Because we know that this is a Kanto festival where Oak appears. But we know that Charizard isn't in the Oak ranch and anywhere in the Kanto region. Is in the Charific Valley, place that is in Johto.
Of course, Ash's Charizard will be in the movie and Episode N but I have doubts that will be appearing in this episode fighting Dragonite.