Among some of the many strange things Crystal has cooked up, one is a type of crystal that can effectively bestow a Mew form on whoever she grants one to, along with a very basic understanding of psychic powers and knowing how to switch back and forth.
The resulting Mews aren't nearly as powerful as a full-fledged Mew, not without some serious effort at least, and can be a little clumsy in general as they adjust, but overall it's a boon.
And a great way to mess with a certain mailman who won't be named here, that looks wonderfully adorable in a dress, and even more fun to tease about it~