Niantic announced that Pokemon Go players can now add Ditto, the shape-shifting Pokemon, to their in-game collections.
With this release, users may capture a Ditto when they think they’re capturing another Pokemon. That is, Ditto will appear on the map as a different Pokemon, and it will only reveal its true identity after it has been captured.
When Ditto is used to train or battle at a gym, it will copy the appearance, types and moves of the first Pokemon it “sees” at the gym, and it will keep this form until the end of the gym battle. Pokemon Go is available to download for free on the iTunes App Store and Google Play.
Readers: Have you captured a Ditto in Pokemon Go"

...