At the GO Fest in Chicago, the last missing Incognito appeared for the first time in Pokémon GO. Incognito is associated with the special research for Celebi.
Which form of Incognito was added to Pokémon GO? The question mark. Incognito is a special Pokémon that has several forms. Each Incognito corresponds to a letter of the alphabet. Additionally, there is the exclamation mark: ! – and the question mark: ?

At the GO Fest, trainers must catch Incognito to get to Celebi
Incognito is related to Celebi at the GO Fest 2018: The mystical Pokémon Celebi first appeared at the Pokémon GO Fest 2018 in Chicago. Here, trainers must complete a five-part special research to encounter Celebi. At the GO Fest, the letters “C,” “E,” “B,” “L,” “I,” appeared, which together spell out Celebi.
Incognito is not a particularly strong Pokémon and is not useful as an attacker or defender. However, since it is so rare, trainers enjoy catching all its forms. Therefore, trainers were also excited about the spawn of the “C,” “E,” “B,” “L,” “I,” forms at the GO Fest.
Do we also need to catch Incognito in Germany for Celebi? We do not know that yet. The speculations suggest that the special research for Celebi is currently only valid for the GO Fest 2018. For the worldwide release of the mystical Pokémon, there will likely be other tasks. Niantic will surely reveal more information after the big fan festival in Chicago.
More Pokémon are coming soon: Niantic recently released an official image showing the 4th generation in Pokémon GO. However, these Pokémon are not yet in the code. What is in the code, are the still missing Pokémon from the 2nd and 3rd generations:
Who among you has already completed the alphabet and now just needs to catch the question mark?