Although lacking a physical body, Spiritomb projects its appearance out of a small rock called the Odd Keystone. The rock is trapezoidal in shape and has two small dots. There is a crack running down the middle, splitting in two near the bottom. The crack in combination with the two dots appears to form a frowning face. Spiritomb's projected appearance is an ethereal composition of swirling purple fog. Its face is set in the middle of the fog and contains green, crescent eyes that are connected to its jagged mouth. Its pupils are composed of a spiral and it is sometimes only seen with one. Swirling around its face are green orbs with yellow centers.
Spiritomb is formed by the collection of 108 spirits being trapped in an Odd Keystone due to misdeeds. Some Spiritomb are up to 500 years old.
Pokémon Mystery Dungeon
Spiritomb first appears when the player and partner were brought into the future by Dusknoir. It serves as the boss of Sealed Ruin, imprisoning Grovyle within a barrier. Spritomb rises from the Odd Keystone and engages the player and partner, but they manage to defeat it and reduce it back to the Odd Keystone. Spiritomb then runs off, releasing its barrier on Grovyle.
In the special episode "In the Future of Darkness" exclusive to Explorers of Sky, Spiritomb is ordered by Dusknoir to hold Celebi hostage in the depths of Icicle Forest to lure Grovyle to an electric field. Spiritomb fakes timidness to draw Grovyle closer to Dusknoir's electric trap. When Primal Dialga attacks Dusknoir for saving Grovyle from the trap, Spiritomb cowardly runs off, releasing its grasp on Celebi. The ending cinematic shows that Spiritomb, along with the other future Pokémon, have survived the future's presumed destruction when Temporal Tower was restored.
Years ago, an evil Spiritomb was causing destruction through the village. Until one day, a man with a Pikachu simply known as the Aura Guardian arrived to confront the evil Pokémon. After a long and grueling battle, Spiritomb was defeated and was sealed inside its own Odd Keystone. To prevent Spritomb from causing any more destruction, the villager created a Hollowed Stone Tower and placed the Odd Keystone in the Tower.
Spiritomb remained in the Tower for so many years. Until one day, when Ash and Dawn were battling each other to test their newly traded Pokémon. Dawn's Aipom used Focus Punch on Ash's Buizel, but she missed. The Focus Punch ended up hitting the Hollowed Stone Tower, which destroyed it. When that happened, Spiritomb was released. Spiritomb attacked the group with a powerful Shadow Ball. Ash's Buizel attacked Spiritomb with Water Gun, but the Water Gun went straight through Spiritomb, dealing no damage. Spiritomb then processed with a Shadow Ball directly at Buizel, knocking him out. After which Spiritomb flew away, dropping its Old Keystone which is found by Team Rocket.
After destroying the village, Spiritomb attacks Pikachu. Team Rocket appears and steal both of them, only for Spiritomb to destroy their balloon with Ominous Wind. Jessie sent out Seviper, but it is quickly defeated by Spiritomb's Hyper Beam. As they run, Spiritomb chased after them. Upon catching up with them, Meowth communicated with Spiritomb, revealing that it wants revenge on the Aura Guardian who sealed it within the Old Keystone.
Dawn plans to trap Team Rocket using Pikachu, and use them to lure Spiritomb. After Team Rocket fall into a pitfall, they trick Spirtomb into believing Ash is the decedent of the Aura Guardian, making it chase after him and Pikachu. After a lengthy battle, Pikachu sends a Thunderbolt towards the sky, recharging his energy, before using a mixture of Volt Tackle and Thunderbolt to defeat Spiritomb, sealing it back into the Old Keystone. The group seal the Old Keystone back into the rebuilt Hollowed Stone Tower.