Mt. Moon Square sits atop the heights of Mt. Moon. The area is small and indented, with rugged mountains surrounding the square at all angles, as if the square was a crater from a cosmic impact. There are two entrances into the square; one from the north end and another from the southern side. On the eastern side there is a small shop, where adventurers who stumble across the square can buy a variety of goods. On the western side there is a strange, mysterious square where Clefairy are said to perform secret rituals.
Despite the full moon being visible only every four weeks in the real world, its reflection is visible here every Monday.
A small shop in the square is open every day from 10:00 am to 5:59 pm. It is there for adventurers who stumble across the secret square. The shop sells a variety of goods, including Portraitmail in the Generation II games, which can only be found at the shop.
In addition to a shop, there is a small, square field next to the shop. If the player ventures to the square between Monday night at 8:00 pm and Tuesday morning at 4:00 am, the player will see two Clefairy dancing around a rock. Once the player enters the square, the Clefairy will be startled and run away, leaving behind Kanto's only breakable rock in the Generation II games, which hides a Moon Stone. However, if the player leaves the area (or enters the shop) before smashing the rock, the rock will disappear and there will be no way to get it back until the following Monday.
In Pokémon HeartGold and SoulSilver, there will be four Clefairy dancing around a pond with the moon's reflection, with two Clefairy standing aside watching. During the dance, a Clefairy will see the player and all the Clefairy will run away, leaving behind an item ball with a Moon Stone inside. Similar to its predecessors, if the player leaves the area before picking up the item ball, the item ball will disappear. As well, even if it is still Monday night, the moon will disappear.
If the game is saved and turned off after the Clefairy event, but before leaving the area, Mt. Moon will still be playing after the game is resumed, the moon's reflection will still be visible in the water, and the shop will still be closed, even if the game is resumed when it is not nighttime.
If the game is saved at the Mt. Moon Square without the Clefairy event and turned off, then resumed at the right time for the event, the result depends on the game:
- In Pokémon Gold, Silver, and Crystal, the event will start normally.
- In Pokémon HeartGold and SoulSilver, the event will still not be available until the player leaves leaves the Mt. Moon Square and returns. Once that is done, the event will start normally (if the player returns within the time required to start the event).
Top panel: The Clefairy dancing; Bottom panel: after they have left
The Clefairy dancing at Mt. Moon Square in HeartGold and SoulSilver