Clefable has been owned by Lusamine since she was still a Cleffa and used to play a lot with Lillie and Gladion when the two were young. At some point, she evolved into Clefairy, and later into Clefable with a Moon Stone against Lillie's wishes, as shown in a fantasy in A Dream Encounter!.
Clefable was first seen as a Cleffa in Lillie's Egg-xhilarating Challenge! in a photograph at Lillie's house where she was shown being held by Lillie. The photo later reappeared in A Glaring Rivalry!. As a Clefairy, she reappeared in a flashback in Mission: Total Recall!, in which she was seen playing with Lillie.
Clefable made her first physical appearance in Faba's Revenge!, when Lusamine sent her out to battle Nihilego, only to be recalled when her energy had been drained. With Lusamine under the control of Nihilego, Clefable was later sent out to stop Ash and Lillie in Rescuing the Unwilling!. She briefly battled Snowy and Ash's Lycanroc before Lillie was able to break Clefable free of Nihilego's control by reminding her of their past together. Clefable appeared again in The Professors' New Adventure!, attending the wedding of Professor Kukui and Professor Burnet alongside its Trainer.
Since A Mission of Ultra Urgency!, she has been stationed at the Ultra Guardians base below the Pokémon School, having been selected by Lusamine to assist Ash and his classmates when they undertake their tasks as the Ultra Guardians. She usually greets them when they first arrive before pointing to the monitor where Lusamine, Wicke, and Professor Burnet will make contact.