Since the release of Ditto in Pokemon Go, I have managed to catch a couple of the sneaky little insert expletive.
But instead of wasting all of my Pokeballs catching every single Pidgey, Rattata, Zubat and Magikarp… is there a way to tell if that Pokemon is a Ditto or not? I'm talking about once I click on the wild Pokemon and it's on my screen ready to be caught.
I did see this question here, but it only asks about seeing Ditto on the radar. And this question but it's in regards to catching the Ditto.
Best Answer
There are, in fact, a couple ways to detect a Ditto:
Dittos have different thresholds for ring colors, which means that their ring colors might not match the expected CP value. For example, a Ditto hiding as a Rattata may have a CP listed as 27, but it may have a yellow or orange ring. Of course, this isn't foolproof as the CP might very well match. This may very well be an unintended mechanic/bug, as per reports by others.
Sources: PoGo Gamepress, Reddit Thread, Various online comments/sources, personal experience, community reports.
If you're clever with reverse engineering and reading the game data, a hiding Ditto is detectable due to a couple flags sent to the client, so everybody knows what is being dealt with. These flags can either be intercepted using something like Wireshark, or you can (try to) use a mapping/radar solution. Of course, this is dependant on Niantic not changing anything, which we never can predict reliably.
However, if the ring colors match (which seems to be rather common) and you don't want to use Wireshark or other "cheaty" methods, there's no way to legitimately detect a Ditto without catching it. And, you don't need a permit for catch-and-release.