Pokémon: Indigo League

The Ancient Puzzle of Pokémopolis (1x74)

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While training, Ash and his friends accidentally uncover the ruins of Pokémopolis, an ancient city. A giant Gengar and a giant Alakazam who were respectively trapped inside a "dark device" and a strange urn are awakened. The two start to fight one another when a giant Jigglypuff appears and puts them to sleep.