From Bulbapedia, the community-driven Pokémon encyclopedia.
Mount Quena is an anime-exclusive location in Johto. It was featured in the special Mewtwo Returns. The mountain contains a lake with water containing healing properties. Pokémon naturalists Luna Carson and Cullen Calix came to the mountain to research about the lake. In the special, Mewtwo and the Pokémon clones were said to have come there after the events of Mewtwo Strikes Back. Giovanni, along with Domino and Team Rocket came here to get back Mewtwo and exploit the healing waters of the lake, sparking the events of the movie, but were later stopped by Ash and his friends. Mewtwo later wiped Team Rocket's memories.