Thinking that it was Ash in disguise, she welcomed it with open arms and treated it like Ash until the real Ash showed up. Still, she treated Mr. Mime like part of the family. Because of Delia's care and affection, Mr. Mime decided to stay with her and help her with her household jobs like making food, cleaning vessels, rooms and also helping Delia in gardening and grocery shopping. Delia, after a short while, decided to name Mr. Mime as "Mimey".
When Brock returned prior to "A Tent Situation", Mimey and Brock would argue about chores and who would do them.
It is unknown what happened to it when Delia Ketchum went on vacation to Unova. It was not seen in Ash's house in "In the Shadow of Zekrom!" However, it appears in the last episode of the Best Wishes saga, "The Dream Continues!" where it is shown that Delia still kept it throughout the Best Wishes series.
In "Alola to New Adventure!", Mimey goes with Delia, Ash and Pikachu to the Alola region. It is revealed that it participated in a lottery and managed to win tickets for all of them. Mimey returns with Delia to Pallet Town at the end of the trip while Ash stays in Alola.
In "Alola, Kanto!", Mimey and Delia were happy to be reunited with Ash when he returns home in Pallet Town with Misty, Brock and five of his Alolan friends to visit at Professor Oak's lab. Both are last seen watching the others eating during sunset.
In "Z-Move Showdown!", the closing ceremony of the Manalo Conference was disrupted by the appearance of a Guzzlord. Mimey accompanied Delia and Professor Oak as they tried to leave, only for a Shiny Guzzlord to block their way. However, it was quickly seen off by Professor Kukui and Ash.
In SS002, Mimey traveled with Delia, Ash and Professor Oak to Vermilion City to attend the opening of the Sakuragi Institute. After Ash and his new friend Go encountered a Lugia and reported this to Professor Sakuragi, the professor decided to make Ash and Go his new research assistants and gave them a room at the institute. Delia then decided to leave Mimey at the Sakuragi Institute so it could watch over Ash.
In SS007, Mimey led a session of kung fu exercise for Go, Koharu, and Professor Sakuragi. Later in the episode, Ash chose to use Mimey as his second Pokémon in the Battle Frontier Flute Cup, much to Go's surprise. It was first used to battle Houji's Hariyama in the tournament finals and easily won. When Houji sent out his Mightyena next, Mimey immediately refused to battle it, forcing Ash to switch it with Pikachu.
- Mimey marks the last role that Kayzie Rogers voiced before she retired.
- The dub mentions Mimey being male.
- Mimey is the first Psychic-type and Fairy-type Pokémon that's owned by Ash.
- It is also the only Pokémon that he has given a nickname to.
- Mimey is the first Pokémon to be owned by both its Trainer and with somebody, Delia.
- Mimey was initially owned by Delia, but it decided to stay with Ash (at the Sakuragi institute) in the New series.
- In SS007 shows Mimey is not without a smuggish trait as a Mr. Mime who appeared Pokémon: Detective Pikachu movie.