A Pokemon GO Evolution Item is required to make certain Pokémon evolve. Trainers can collect Evolution items by spinning PokéStops. Drop rates for evolve items are fairly low (0.76% – 1%). However, trainers can get 1 guaranteed, albeit random, Evolution Item by completing their “First PokéStop (or Gym) of the Day” 7-day streak. 

There are currently 5 Evolution Items available in Pokémon Go:

Sun Stone King’s Rock Metal Coat Dragon Scale Up-Grade
 Bag_Sun_Stone_Sprite.png  Bag_King's_Rock_Sprite.png  Bag_Metal_Coat_Sprite.png  Bag_Dragon_Scale_Sprite.png  Bag_Up-Grade_Sprite.png
In-game text: A peculiar stone that can make certain species of Pokémon evolve. It burns as red as the evening sun. In-game text: A rock that can make certain species of Pokémon evolve. It looks like a crown. In-game text: A coating that can make certain species of Pokémon evolve. It is a special metallic film. In-game text: A scale that can make certain species of Pokémon evolve. It is very tough and inflexible. In-game text: A transparent device that can make certain species of Pokémon evolve. It was produced by Silph Co.

The table below shows Evolution Items and the related Pokémon to evolve:

Evolution Item Pokémon to Evolve Candy Cost Evolved Form
Sun Stone Pokemon GO GloomGloom 100 Oddish Candies Pokemon GO BellossomBellossom
Sun Stone Pokemon GO SunkernSunkern 50 Sunkern Candies Pokemon GO SunfloraSunflora
King’s Rock Pokemon GO SlowpokeSlowpoke 50 Slowpoke Candies Pokemon GO SlowkingSlowking
King’s Rock Pokemon GO PoliwhirlPoliwhirl 100 Poliwag Candies Pokemon GO PolitoedPolitoed
Metal Coat Pokemon GO ScytherScyther 50 Scyther Candies Pokemon GO ScizorScizor
Metal Coat Pokemon GO OnixOnix 50 Onix Candies Pokemon GO SteelixSteelix
Dragon Scale Pokemon GO SeadraSeadra 100 Horsea Candies Pokemon GO KingdraKingdra
Up-Grade Pokemon GO PorygonPorygon 50 Porygon Candies Pokemon GO Porygon2Porygon2

Note: Pokémon requiring Evolution Items are not typically found in the wild.

Evolution Items are used for both normal and split evolutions:

 Normal Split
 

Check out these guides to find out more about Evolution Items: