Smeargle may appear in photos taken using the GO Snapshot feature and will attempt to copy the moves of the Pokémon that was the subject of the photo. If one appears in a photo, it will show up on the Trainer's Map View after exiting the photo gallery.
Smeargle - Painter Pokémon
Smeargle marks the boundaries of its territory using a body fluid that leaks out from the tip of its tail. Over 5,000 different marks left by this Pokémon have been found.