In the Pokémon world, there are many different dimensions. While trivial references to other dimensions were made early in the franchise's history, the concept was truly introduced in Generation IV. Four of the Sinnoh region's legendary Pokémon have a connection to alternate dimensions which are an aspect of the main plot of Pokémon Diamond, Pearl, and Platinum; this is expanded on in the Diamond & Pearl series Pokémon movies.
- Main article: Unown dimension
While researching ruins with depictions of the Unown, Spencer Hale was transported into this dimension. His daughter, Molly, inherited a puzzle box found there that gave her contact with the Unown, which granted her wishes. Such was the strength of the world she created, that an opening to the dimension appeared in the entrance hall of her mansion. During this time, the Unown gained powerful control over Greenfield, but all contact with the dimension ended after Molly wished for things to go back to the way they had been before. A portal to the dimension was opened above Mt. Silver some time later, and an Unown fell out, but it had no trouble returning when it was in good health. This dimension also became the battleground of Dialga and Palkia, before their battle moved to Alamos Town.
Travel between this dimension and the real Pokémon world has been shown to be possible through a puzzle box and a portal.
- Main article: Ghost World
In the anime an entrance to it appeared in Ghoul Daze!, where the Pokémon Summer Academy staff accidentally opened a portal to it when renovating the Summit Ruins. A ghost girl and Dusknoir were both let out, with the Dusknoir trying to take the ghost girl back to the Ghost World, while she was trying to abduct people and take them to the Ghost World. Another entrance appeared in Scare at the Litwick Mansion!, where the Litwick in Litwick Mansion tried to lead Ash and his friends there while draining their life energy.
- Main article: Mirror World
The Mirror World is an alternate dimension with strong connections to the Reflection Cave. It is nearly identical to the regular Pokémon world, with the exception that the humans and Pokémon found in the Mirror World have opposing personalities to their regular world counterparts. According to Mirror Clemont, the existence of portals to other worlds in the Reflection Cave is a myth, at least in the Mirror World. This also suggests the Mirror World is merely one of many different alternate dimensions reachable through the Reflection Cave. Also according to Mirror Clemont, people not from the Mirror World will be trapped inside the Mirror World forever once the sun has set, although the regular world's Team Rocket managed to get out somehow even though they were still in the Mirror World after sunset.
It appeared in The Cave of Mirrors!. Ash wandered in the Mirror World after he was lost in the Reflection Cave and his mirror image took Pikachu from his shoulder. In the Mirror World, Ash met up with the Mirror World counterparts of Serena, Clemont and Bonnie, and later also with the Mirror World counterpart of himself. Later, the Mirror World counterparts of Ash and his friends helped the regular world's Ash to get back to his own world before sunset.
A device called the Time-Space Axis in Michina Town is able to indicate the condition of every minute change in the time-space continuum, serving to mirror the movements of the timespace dimensions and thus monitoring the likelihood of potential cataclysm.
- Main article: Distortion World
The Distortion World is first accessed when the player reaches the summit of Mt. Coronet, the Spear Pillar, to stop Team Galactic's plot to control Dialga and Palkia. When the Lake guardians are unable to control both Dialga and Palkia, Giratina comes and swoops on Cyrus to stop him from destroying the world. After Cyrus is taken away by Giratina, the player must follow him, and with the help of the lake guardians and Cynthia, navigate the area. The Distortion World is said to be another universe or world parallel to the Pokémon world. Two known gateways to it exist: one at the top of Mt. Coronet on the Spear Pillar, and another in Turnback Cave. It is a dark place with floor-like sections floating at many different angles. The world disobeys the normal laws of physics, allowing the player to walk and surf on walls in any direction. The only Pokémon known to inhabit the Distortion World is Giratina.
In the anime, it is referred to as the Reverse World.
It and the Spatial World are usually far away from each other, but due to shock waves caused by Arceus awakening from its deep slumber, they clashed. This resulted in a battle between Dialga and Palkia, because each Pokémon thought that the other was trespassing onto its territory. It subsided a short time before Arceus woke up.
In Diamond and Platinum, Cyrus summons Dialga from there. In Platinum, when the player battles Dialga after entering the Hall of Fame, it comes through a dimensional rift created by Cyrus's original summoning of it.
It and the Temporal World are usually far away from each other, but due to shock waves caused by Arceus awakening from its deep slumber, they clashed. This resulted in a battle between Dialga and Palkia, because each Pokémon thought that the other was trespassing onto its territory. It subsided a short time before Arceus woke up.
In Pearl and Platinum, Cyrus summons Palkia from there. In Platinum, when the player battles Palkia after entering the Hall of Fame, it comes through a dimensional rift created by Cyrus's original summoning of it.
Flavor text references to other dimensions