Evolution Items are items used to evolve certain species of Pokémon. There are currently six items that can be obtained, that are:
and Sinnoh Stone.
Unova Stone coming to the gameplay soon.
To see currently owned Evolution Items player can check them out on the
item bag page .
Details Evolution Item that is required to evolve Seadra into Kingdra.
A scale that can make certain species of Pokémon evolve. It is very tough and inflexible.
Details Evolution Item that is required to evolve Poliwhirl into Politoed and Slowpoke into Slowking.
A rock that can make certain species of Pokémon evolve. It looks like a crown.
Details Evolution Item that is required to evolve Onix into Steelix and Scyther into Scizor.
A coating that can make certain species of Pokémon evolve. It is a special metallic film.
Details Evolution Item that is required to evolve Gloom into Bellossom and Sunkern into Sunflora.
A peculiar stone that can make certain species of Pokémon evolve. It burns as red as the evening sun.
Details Evolution Item that is required to evolve Porygon into Porygon2.
A transparent device that can make certain species of Pokémon evolve. It was produced by Silph Co.
Details Evolution Item that is required to evolve many Pokémon into Sinnoh-region Pokémon.
A special stone originally found in the Sinnoh region that can make certain species of Pokémon evolve. It is very tough and has a beautiful sheen.
Details Evolution Item that is required to evolve many Pokémon into Unova-region Pokémon.
Research Breakthrough or participating Trainer Battle has a small chance to obtain it.
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.
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 were mentioned.
The Sinnoh Stone was first discovered in network traffic on November 6 th, 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.
Similarly to Sinnoh Stone, graphic design of Unova Stone is made of black and white materials which is reference to Pokémon: White and Black games in which Unova region was introduced.
During Hatchathon, claiming Research Breakthrough guaranteed a Sinnoh Stone.
During the February 2019 Community Day, Trainers were guaranteed to receive up to five Sinnoh Stones as a reward from Trainer Battles; in order to evolve their Piloswine into Mamoswine.
No Sinnoh Stone was guaranteed on August 2019 Community Day for Gallade evolution.
Porygon family is the only evolutionary line that requires two different evolution items.
Evolving your Pokémon. Pokémon GO Support. Retrieved on 2017-14-12.
New item: Sinnoh Stone!. /r/TheSilphRoad. Retrieved on 2018-11-13. ↑ NianticHelp. (2019, January 23).
Allow us to clarify further. Twitter. Retrieved on 2019-08-04.