The original Trainer (Japanese: おや owner), or OT, of a Pokémon is the Trainer who caught or hatched the Pokémon in question first. The original Trainer's name is used in conjunction with their ID number to verify which Pokémon are outsider Pokémon by the games.
In the games
Pokémon receive the OT of the Trainer who originally caught, hatched, received, or snagged the Pokémon. NPC Trainers who give away Pokémon for free will not be registered as the Pokémon's OT, except for in two instances - a Spearow given by Webster and a Shuckle given by Kirk, both in the Generation II games and their remakes. These special instances are different in that the Pokémon received is intended to be later returned, in Webster's case to his friend on Route 31, and in Kirk's case, to him after Silver has been defeated at Mt. Moon.
A Pokémon bred by a player which is traded as an Egg to another will be registered to the hatching Trainer, while the breeder will not matter. A Shadow Pokémon that has been snagged will initially display its OT as question marks, however, after becoming purified, it will have the person who purified it as its OT, with no mention made of the Trainer it was snagged from.
A Pokémon whose original Trainer is not the same as its current Trainer is called an outsider Pokémon; this is determined by using the original Trainer's name, Trainer ID number, Secret ID, and gender. Outsider Pokémon may disobey its Trainer in battle if they lack the appropriate Badges (but they will always obey in link battles). Outsider Pokémon gain 50% more experience than Pokémon trained by their original Trainer; from Generation IV onward, outsider Pokémon whose language of origin is different to the game's language instead gain 70% more experience.
Only the original Trainer of a Pokémon can change the nickname of a Pokémon.
Prior to Generation VI, due to a glitch, if an Egg is hatched in a game other than that of the player who generated it, it can hatch with the appearance of a Shiny Pokémon in the cutscene but actually be normally colored, or hatch normally colored but actually be Shiny. This is because the Egg has the same Trainer ID number and Secret ID as the player who generated it before the cutscene, but they change to match the hatching player after the cutscene. This also allows Eggs that are normally prevented from being Shiny (Eggs obtained from event distributions and the Manaphy Egg) to be Shiny, as long as they are hatched in a game other than the game that generated them. In Generation VI, this can no longer happen.
In Black 2 and White 2, the player will have the opportunity to catch Pokémon that were once used by N via the Memory Link. Though the player is the one that catches these Pokémon, the Pokémon will have N as the OT, making N's Pokémon outsider Pokémon. Like other outsider Pokémon, N's Pokémon receive boosted experience points.
Special original Trainers
- Main article: List of notable ID numbers
Sometimes, there are special original Trainer names assigned to Pokémon if they come from a non-standard Pokémon game or are received as a prize.
- The OT will be highlighted as blue if it is a male Trainer and red if the Trainer is female in Generations III (except in Pokémon FireRed and LeafGreen), IV and V. In Korean games, female OTs are highlighted in pink instead of red.
- In the Japanese versions of the Generation III games, Western OT names (like Western Pokémon names) are rendered as fullwidth characters, which limits the display of names to five characters.