Evolution Items

Evolution Items are items used to evolve certain species of Pokémon. There are currently six items that can be obtained, that are:
 * Dragon Scale,
 * King's Rock,
 * Metal Coat,
 * Sun Stone,
 * Up-Grade
 * and Sinnoh Stone.

To see currently owned Evolution Items player can check them out on the item bag page.

Sinnoh Stone
Claiming Research Breakthrough or participating Trainer Battle has a small chance to obtain it.

Others
There is small chance that they can be obtained from spinning Photo Disc in PokéStops and Gyms and trainer is guaranteed one on their seventh day spin streak. They can be also obtained as a reward from research tasks and gifts.

Trivia

 * All Pokémon, that to evolve into them there is evolution item required, cannot be neither caught in the wild, hatched from an egg nor be a Raid Boss in the gym and the only way to acquire them is the evolution.
 * Historically, in the Pokémon game core-series, the following conditions described below will take place when one of these items are given to a Pokémon to hold:
 * Pokémon capable of holding either a Dragon Scale, King's Rock or Metal Coat will evolve when traded.
 * Pokémon capable of holding either a Sun Stone or Up-Grade will evolve when leveled-up.
 * On the official support page for Pokémon GO, Deepsea Scale and Deepsea Tooth are mentioned.
 * In the main series games, these items are required to evolve Clamperl into either Huntail or Gorebyss respectively.
 * The Sinnoh Stone was first discovered in network traffic on November, 2018.
 * Graphic design of Sinnoh Stone hints that it is made of diamond and pearl materials which is reference to Pokémon: Diamond and Pearl games in which Sinnoh region was introduced.
 * During Hatchathon, claiming Research Breakthrough guaranteed a Sinnoh Stone.