In Pokemon Go, Ditto is a Transform Pokemon that can disguise itself as other Pokemon on the map, making it difficult to catch. When you tap on a disguised Pokemon, it will stay as that Pokemon until you catch it, at which point it will transform into a Ditto. The disguises that Ditto can take on change periodically, so its important to stay up to date on the current disguises if youre trying to catch one. As of September 2023, Ditto can disguise itself as Diglett, Grimer, Snubbull, Corphish, Starly, Roggenrola, Tympole, and Litleo. It is also possible to catch a shiny Ditto, but the odds are random and not tied to any specific disguise. To increase your chances of catching Ditto, you can use items like Incense and Lure Modules to attract more Pokemon to your location.