Mt. Moon (オツキミやま; Mt. Otsukimi) is a mountain found in Kanto. Found on Route 3, the mountain lies between Pewter City and Cerulean City. The inside of the mountain contains a multitude of interconnecting caves, and various Pokémon. It is fabled for containing Moon Stones.
In an attempt to find out more about Team Rocket, Red and Misty head into Mt. Moon. Using Professor Oak's information, they search for the Moon Stone, which is also the target of Team Rocket. Once inside one of many caves, the two soon stumble upon Koga and various Team Rocket grunts. Though victorious at first, an experimental serum allows for Koga to attain the upper hand. It is only through causing a partial collapse of the cave that the two are able to escape. In the end, Red victoriously reveals he found the Moon Stone.