There's a swath of new evolution items that you can use on your quest to catch them all, and the King's Rock is one important item. Here's everything you need to know about using the King's Rock.
Pokémon Go: What to do with the King's Rock
According to IGN, the King's Rock is an evolution item you can use alongside Pokemon Candy in order to evolve certain Gen 1 Pokémon. There are currently two Pokémon that you can use the item with: Slowpoke and Poliwhirl.
You can use the King's Rock, along with 50 Slowpoke Candy, to evolve Slowpoke into Slowking. If you try evolving it without this item you'll get a regular Slowbro instead.
You can also use the King's Rock combined with 100 Poliwag candy to evolve Poliwhril into Politoed. If you evolve it without the item you'll get Poliwrath.
Just like with the rest of these new evolutionary items, the only way to get them at the moment is by spinning PokéStops. So if you're determined to get a King's Rock you'll want to hit your local PokéStops as often as possible.
More Pokémon Go guides, tips, tricks and updates
Check out Mic's guides on how to get stardust, how to determine how long it will take you to reach level 40, the kind of Pokémon you get from 10km eggs, how to create new PokéStops, how to maximize your chances of catching Pokémon and how PokéStops distribute Pokémon eggs. Also check out how to catch Gen 2 baby Pokémon, our analysis of post-balance update Chansey and Rhydon and everything you need to know about finding the long-awaited Pokémon Ditto.