In Pokemon Go, Ditto disguises itself as other Pokemon, making it difficult to catch. The disguises change periodically, so its important to know the current list of disguises if youre trying to catch Ditto. As of October 2023, Ditto can be disguised as the following Pokemon:

• Diglett (Gen 1, Kanto)
• Grimer (Gen 1, Kanto)
• Snubbull (Gen 2, Johto)
• Corphish (Gen 3, Hoenn)
• Starly (Gen 4, Sinnoh)
• Roggenrola (Gen 5, Unova)
• Tympole (Gen 5, Unova)
• Litleo (Gen 6, Kalos)

When you catch a Pokemon that is actually a Ditto in disguise, you will see an "Oh?" prompt and the Pokemon will transform into Ditto. Its worth noting that shiny Pokemon will not transform into shiny Ditto, and Ditto can only be found disguised as another Pokemon.