Not Mewtwo or Zapdos, that Lugia was chosen by Niantic to be the first legendary Raid Boss in Pokémon GO also the first legendary Pokémon to appear in this game.
At Pokémon GO Fest taken place in Grant Park, Chicago fans of Pokémon GO are able to fight against Lugia and own this legendary Pokémon.
Niantic reveals that it will take another 48 hours after the event at Grant Park for the new Raid Boss Lugia to appear and that it is time for the gamers to catch this legendary Pokémon. Besides Lugia, Articuno is also another legendary Pokémon appearing in the Pokémon GO. Maybe in the future Pokémon GO will be extremely hot and regain its attraction with the appearance of the legendary Pokemon.