A member of Niantic's executive team has advanced that we will have "a legendary summer" for Pokémon GO. The use of this word has been totally deliberate, giving rise to think that legendary creatures will be added in the game on the occasion of their first anniversary in July.
At the moment, with respect to the Kanto region only the legendary Pokémon - including Articuno, Zapdos, Moltres, Mew and Mewtwo- can not be captured in any way in the game, but with the recent declarations of Archit Bhargava of Niantic in the 21st Annual Webby Awards, it seems that the situation will change radically in this sense in a way yet to be determined.
"This summer is going to be legendary," said Bhargava. Although this does not confirm at any time that Articuno, Zapdos and Moltres will finally have their respective event in the game, there are reasons to trust more than ever that Pokémon GO will finally make available to iOS and Android players at Legendary birds.