Back in May of this year, an anonymous user on 4Chan posted what they claimed to be a bunch of information about Pokemon Sword and Shield. At the time the information was posted, no one really took it seriously. However, Nintendo's announcements about Pokemon Sword and Shield have continuously proven the leak correct, and in fact, almost every single detail mentioned in the leak has been confirmed by now. The latest leaked Pokemon Sword and Shield bit of info that's been confirmed is the existence of Farfetch'd's evolution Sirfetch'd, and so one of the only remaining info from the leak that has yet to be corroborated has to do with the starter evolutions.
The same leaker who leaked Farfetch'd's evolution and a bunch of other information about Pokemon Sword and Shield also revealed some information about the starter evolutions. According to the leaker, Scorbunny will be a pure fire-type Pokemon throughout its evolution line, and it will eventually evolve into a creature named Raboot. Even though Scorbunny will be a pure fire-type, it will apparently learn fighting-type moves and resemble a fighting-type Pokemon.
Sobble, meanwhile, will evolve into Sizzle, and then finally Intelleon. Apparently, Sobble's evolution line will give the Pokemon a spy-theme, which is not what one would expect from Sobble. And finally, Grookey's final form is said to be a giant gorilla armed with a wooden drum. While it's possible that the leaker is off about the Pokemon Sword and Shield starter evolutions, since almost everything else in the leak has been accurate, it's safe to say that the info about the starter evolutions is as well.
Dynamaxing and Gigantamaxing have also been confirmed for Pokemon Sword and Shield since the leak was posted, as has the existence of the Team Rocket-like group Team Yell. Really the only other major bit of information from the leak that has yet to be confirmed, besides the starter evolutions of course, is the existence of an "evil" legendary Pokemon named Eternatus.
The leaker correctly predicted the other Pokemon Sword and Shield legendaries that have been revealed so far, so it stands to reason that they're on the money in regards to Eternatus as well. It will be interesting to see what it and the starter evolutions look like when they're finally revealed in an official capacity.
Pokemon Sword and Shield launches on November 15, exclusively for the Nintendo Switch.