Elizabeth's Ditto

Elizabeth's Ditto was the fourth Pokémon caught by Elizabeth Storybook in Alola, and her sixth overall.

History
Ditto first appeared near the end of the episode Kirlia the stalker, at the edge of the parking lot of a grocery store that Elizabeth and Rotom were walking through on their way home, disguised as a Rotom.

It then showed up at Elizabeth's house the next day, having been invited by Rotom and explaining that the two of them had been friends for a very long time, since they were very young. Like Rotom, it was taken care of by her for a while before being caught.

In the episode New traveling companion, while the three of them were taking a stroll on Route 10, nearMount Hokulani, Elizabeth offered to catch both Ditto and Rotom, to which they accepted and let themselves be caught by her.

Personality and characteristics
Ditto is very close with and very protective of Rotom, and it is revealed that it can feel when Rotom is suffering or feeling sad and will teleport to its aid (transformed into a Pokémon that can do so) when necessary, for example to protect or comfort it. Both Manaphy and Rotom have an intense crush on it, sometimes fighting. For this reason Elizabeth keeps it at the laboratory in Storybrook Village, to prevent them from injuring Ditto, each other, and themselves.

It enjoys transforming into things that aren't living, or are simply strange, such as dishes, its Trainer, or, on one occasion, a pretty girl with green skin. It also senses Rotom's current mood and what it's doing at the moment.