Episode 933: The Finals! Ash VS Alain!! Episode 934: Kalos League Victory! Ash's Ultimate Match!! Episode 935: Team Flare Attacks! The Zygarde at the Prism Tower!!
Ash loses against a rival at some point and beats them in a rematch. Ash loses because of the Ash-Greninja form failing. He has since learned to control it. Ash battles and loses to Diantha because of the Ash-Greninja form failing.