Pokémon starts by celebrating unique evolutions through an Evolution Event, highlighting the creative ways in which Pokémon evolve throughout the series. Many of these evolutions sometimes require the trainer to increase a Pokémon's happiness, while others require a particular stone.
In this event, you have a chance to acquire two special stones, the Unova Stone and the Sinnoh Stone. Trainers will need these to evolve specific Pokémon in their group into transformations specific to the Sinnoh and Unova region.
Fortunately, trainers shouldn't have too much time to acquire these useful stones and use them on their favorite Pokémon. You can receive them by carrying out research activities in the Evolution event.
Receive a Sinnoh Stone by completing the quest to hatch seven Pokémon Eggs and receive the Unova Stone by winning three battles against Team GO Rocket Leaders.
You can probably complete these tasks in one go as it takes a bit of work to locate a Team GO Rocket Leader, so make sure you have several incubators on hand and have some low-range Pokémon Eggs that you can throw into them .
The Evolution event continues until December 12th at 13pm PST.