Thinking that it was Ash in disguise, she welcomed him with open arms and treated him 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 their 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 "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, he appears in the last episode of the Best Wishes saga, The Dream Continues! where it is shown that Delia still kept him throughout the Best Wishes series.