We all know that the Legendary/Mythical Pokémon are missing from Pokémon GO, but there is another Pokémon missing: Ditto. Ditto is no Legendary, and yet, it has been excluded. Why? It has been said that Ditto was never released so that it could be released during an event, but is that the only reason?
Ditto is very different from other Pokémon. Its gimmick is that it shapeshifts into whatever Pokémon it is battling. Ditto not only steals that Pokémon’s look, but its other attributes as well, including type, ability, and move set. The real reason Ditto was not released right away is because battling with Ditto would be totally different than battling with any other Pokémon, and Niantic did not know how to include it.