In its natural state, Ditto is a light-purple or pink blob-like Pokémon with vestigial facial features. It is often referred to as amorphous, but has a relatively consistent appearance in official artwork, including two small nubs on its "head", a few soft lumps at its base, and two pseudopod-like protrusions in place of arms. The face consists of beady eyes and a simple mouth; almost always pulled into a smile.
It is capable of transforming into an exact replica of any physical object or living creature, including its form and abilities. Each Ditto has its own strengths and weaknesses when it comes to transforming; being unable to remain transformed while laughing and getting details of its transformation wrong if based on memory being apparently universal. The anime and the TCG have shown that occasionally Ditto cannot change its face during transfomation; a trait that has become synonymous with the species despite being incongruous with their depiction in core series games. While its transformation ability allows it to get along with almost anything, it does not get along with its own kind, which it will quickly (and generally fruitlessly) attempt to transform into. It transforms into a rock when sleeping to avoid attack.
In Ditto's Mysterious Mansion, Duplica and her Ditto used to perform for people, but the two had not had an audience since people saw that Ditto could not change its face. Ditto fixed that problem near the end of the episode, when it was captured by Team Rocket.
Sometime before Imitation Confrontation, Duplica found another Ditto, which she nicknamed Mini-Dit. This second Ditto could transform into an exact mirror image of anything, but it could not change its size.
In A Talent for Imitation!, a Ditto works as a film actor because Transform is unusually efficient for impersonations. Its latest role was in a movie directed by Kublock, about Gardevoir twins, but it ran away due to Kublock's overly strict attitude and its increasing inability to use Transform as effectively. Ditto eventually ran into and befriended Team Rocket, who taught it how to overcome its nerves and regain its confidence. As a result, it returned to the set and production resumed without any further problems.
In Tauros the Tyrant, Ditto is one of the members on Green's team. As a master of transformation, Green uses Ditto extensively in her schemes, such as morphing over her face to disguise her appearance (like when she infiltrated the Silph Co. building disguised as Sabrina), camouflaging into its background for subterfuge, as well as forming a protective shield with Green's umbrella.
Ditto was originally intended to be one of the Pokémon randomly released from a Poké Ball. It would have transformed into a copy of the user's character and aided them in battle. However, processing problems forced its removal before the game's release. Ditto can be still be unlocked through the debug menu (which is only accessible through the use of Action Replay), though it does not do anything other than give 7-8% damage to those who touch it.
As for its official status, Ditto only appears as a random trophy and as a cameo in the Tournament Mode menu. In Winner Out or Loser Out tournaments, holding down L and R and pressing A will give the player a random character and color. The usual character image will instead be taken by a picture of Ditto.
Every Ditto has the ability to copy a Pokémon's entire cell structure in an instant and become its exact replica. They're terrible at remembering techniques, but when they use Transform, they temporarily learn all of their foe's moves. If a Ditto starts to laugh, it weakens and can't hold its transformation.
Ditto appears as a Pokémon summoned from the Poké Ball, where it uses Transform to duplicate the shape of the summoning character while still maintaining its own color. It then attacks opposing fighters. Ditto also appears as a Spirit.
Pokémon Pinball: Ditto appears on the Red Table blocking the evolution cave, once the evolution arrows are lit, it moves out of the way, allowing the player to evolve one of the Pokémon they have captured.
Pokémon Trozei!: Ditto serves as a "wild card", meaning it can Trozei with any Pokémon and must be used to get rid of Jammer Balls. One will appear when a Trozei is made with more Pokémon than necessary and multiple appear at the beginning of a new round in Endless and Forever mode to clear out the remaining Pokémon.
Ditto first became available in Pokémon GO on November 23, 2016, disguised as other Pokémon in the wild. Players will only find out whether a Pokémon is a Ditto if successfully captured, upon which a cutscene will show the Pokémon transforming back into Ditto. Ditto can be used in Gym and Raid Battles, in which it will Transform into the first Pokémon it sees; however Ditto cannot be used in Trainer Battles.
As of September 1, 2021, wild Ditto may be Shiny, and some Pokémon whose Shiny forms are available may transform into Ditto. If a player encounters a Shiny Pokémon in the wild, it cannot be a disguised Ditto, but non-Shiny Pokémon have a small chance of being a Shiny Ditto.
As of September 1, 2021, wild Ditto may be disguised as any of the following species:
Ditto is one of two Pokémon to have two different species-specific Stat-enhancing items associated with it, the other being Clamperl. Ditto's two associated items, the Metal Powder and Quick Powder, seem to be the same colors as Ditto's normal and Shiny forms, respectively.
In Pokémon Rumble, since Transform was not programmed into the game, Ditto can only know Struggle. Since PP does not exist in Rumble, this makes Ditto the only Pokémon in Rumble that can use Struggle. However, Transform does exist in Pokémon Rumble Blast, so Ditto has a move from that game onward.
Ditto is the most common Pokémon in Pokémon Trozei!, appearing in every area. This is due to its ability to transform, enabling the player a way to advance further if no links are available before Ditto appears.
In Pokémon GO, Ditto appears in the wild disguised as other Pokémon. After being caught, it will reveal its true form. At one point, a large amount of Ditto were seen disguised as the then-unrevealed Mythical Pokémon, Meltan.
In Generation I, if the player manages to capture an 'M (00), it will still be in battle with the player, and the battle will not end. Catching 'M (00) again results in the second one becoming a Ditto of the same level.
In the sixth issue of Best Buy's @Gamer magazine, Game Freak developers Junichi Masuda and Ken Sugimori revealed that Ditto was originally based on the iconic smiley face. Its eyes and mouth are exactly like ":)", which is an emoticon representing the smiley.
Additionally, Ditto strongly resembles an amoeba, a single-celled organism with no definite shape. This may emphasize its ability to alter its cellular composition. This could also explain why Ditto is unavailable through breeding, since single-celled organisms reproduce differently from multi-cellular plants and animals. It also could partially be based on an undifferentiated cell, a cell in the body that can change into any other cell by sampling it. In addition, it could have been based on a blob or modeling clay.
Ditto's name is the English word ditto, meaning "that which has been said before" (itself from Italian, where it means "having been said"). It was also a brand name for spirit duplicators, and came to mean copies of master documents created by those duplicators.
Metamon is a combination of metamorph and monster. Alternatively, Meta as a prefix can mean "all-encompassing," which Ditto's Transform move does do to Pokémon.