Pokémon GO will host GO Fest 2021 from July 17th – July 18th this summer. We have been told very little about the event so far, so let's see if we can cook up some theories about what is to come in this blockbuster event. Remember, this is going to be taking place during Niantic's fifth anniversary with the franchise and the overall 25th anniversary of Pokémon as an IP. I believe we can expect some truly special releases. Here are my predictions for Legendary Raids that we will see released during GO Fest 2021.
I believe that GO Fest 2021 will go one of two ways: a major Shiny release or a major "new" species release. I gravitate toward the latter because Niantic knows by now that, no matter what, Shiny Pokémon get more hype in raids. While my first instinct is to say that they would release Palkia and Dialga in their Shiny forms in Pokémon GO for the first time, putting more thought to it makes me question that idea. They will know very well that Palkia and Dialga's long-delayed Shiny release is going to be a huge event in the game itself. It doesn't need the GO Fest boost and, in fact, releasing those the same day as GO Fest might lead to people spending all day raiding and doing nothing else.
My current thought is that Zekrom, Reshiram, and Kyurem will return to raids with a new feature of Fusion added, leading to the official release of Black Kyurem and White Kyurem. (This could be related to the "Form changing" we saw datamined earlier this year.) If this is what happens, I predict that they will remain in raids for the week following GO Fest, following the Mewtwo/Articuno/Zapdos/Moltres model from Pokémon GO Tour Kanto earlier this year.
Let us know what you predict will happen with the Legendary Raids for Pokémon GO Fest 2021!