The first rule is that if one of Pokémon which can be a Ditto - such as Diglett - appears in its shiny form when you attempt to catch it, this Pokémon will not transform into a Ditto.

Shiny Ditto has a 1 in 64 chance of appearing ... Furthermore, Ditto can transform into the first Pokemon it meets in battle when used in Gym attacking or defending. This transformation will ...

Ditto can be one of the trickiest to catch in Pokémon Go thanks to its disguises mechanic, one where keeping up with its current rotation is essential to adding the Transform Pokémon to your ...