Pokémon The Series: Sun & Moon

The Lighting Bolt that Severs the Wind! Its Name is Zeraora!! (21x56)

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While training for a possible Island Challenge/Grand Trial on Poni Island, Satoshi and Pikachu meet Kapu-Kokeko and ask to battle it. During the battle, something strange happens and Satoshi and Pikachu find themselves in a ruined city. They meet a mysterious trainer named Dia and a pokémon named Zeraora and learn that an Ultra Beast named Akujiking was responsible for the massive destruction and because the Island Guardians have fled Z-moves no longer work... Why does this ruined city and a particular destroyed building seem so familiar?