In an announcement made this Tuesday, the fifth generation of Pokémon was confirmed for Pokémon GO.
The news was announced in a post on the game's blog, where the team reveals the events that will take place in the game from September 2 to 23, as well as certain bonuses unlocked thanks to players' progress in a global challenge. The new Pokémon will begin appearing in the game on the 16th.

The new addition had already been introduced discreetly in official artwork
When it launched in 2016, Pokémon GO featured only the franchise's first-generation Pokémon, which originated in the Kanto region. Over time, the game was updated with new features and new Pokémon. The developers have already established that they want to implement every generation in the app.
The franchise's fifth generation introduced more new Pokémon than any other, with a total of 156. It is represented by Pokémon Black & White and their sequels, Pokémon Black 2 & White 2. The games take place in the Unova region, based on Manhattan in the United States, and this influenced some of their designs.

Braviary, one of the Pokémon inspired by American culture
Despite the high number of creatures, only 16 of them will initially be released in the app. This has already happened when new generations were added to Pokémon GO, with the game releasing more content "little by little."
There are even still some Pokémon that have not yet been released (such as Kecleon from the third generation). Therefore, the Unova Pokémon can be expected to be released gradually.