The most notable feature of this event is the release of Shiny Kricketot, which will be appearing in the wild for the first time. Mareep, Skitty, Roselia, Kricketot, Blitzle, Cottonee, Minccino, Gothita, and other Pokémon will also have increased spawn rates throughout the duration of the event.
Niantic is also adding even more Pokémon with hats to the game with this event. Smoochum hatched from seven kilometer eggs will have bows on their heads, Kirlia and Shinx from raids will have top hats, and Croagunks will have backwards caps. It’s unknown if these Pokémon will be able to evolve and keep their hats, but based on recent similar events, it’s likely that they will not be able to evolve at all.
While not particularly great for any bonuses, the event will be good for those who still need Gothita, Cottonee, and Minccino candy to evolve the creatures.