That is Dorian Tyrell from The Mask.

“The shutdown effects the Bureau of Alcohol, Tobacco, Firearms and Explosives”

Another reason Ditto may not be available is because Ditto’s only ability is to copy the look and moves of the pokemon it is battling. This type of combat is completely unique to Ditto, and it would not surprise me if Niantic had not yet implemented this special case for Ditto.