The new Pokémon can only be found in eggs, which can be obtained from PokéStops. Eggs are hatched by walking a set distance with the iPhone. Niantic and The Pokémon Company are keeping some of the new Pokémon a secret, and have only announced Togepi and Pichu.
From December 12 at 10:00 a.m. Pacific Time to December 29 at 11:00 a.m. Pacific Time, Pokémon Go players have a chance to catch a special holiday-themed Pikachu, who is wearing a festive hat for the holiday season. Niantic says the new Pikachu will "appear in large quantities.
"Fans around the world fell in love with Pokémon GO for the opportunity to encounter Pokémon--beloved pop-culture and gaming icons for 20 years--in the real world. Matched with the innovative technology and development of the mobile game by Niantic, hundreds of millions of players have filled their Pokédexes with over 100 available Pokémon in Pokémon GO while exploring the world around them," said J.C. Smith, senior director of consumer marketing at The Pokémon Company International. "The opportunity to hatch select Pokémon originally discovered in the Johto region is just the beginning of how more Pokémon will be added to the game for Trainers to continue their Pokémon GO adventures."
Niantic has also established partnerships with companies like Sprint, which will see 10,500 Sprint, Boost Mobile, and Sprint at RadioShack locations turned into PokéStops and Gyms.