Evolution is a game mechanic that allows Trainer to make Pokémon stronger and more advanced by feeding it with certain amounts of Candy. Evolved Pokémon generally has higher CP and HP, usually making them a more valuable for battles.
To evolve Pokémon, player needs to:
- select a Pokémon to evolve from their Pokémon collection page
- in Pokémon's summary page tap on the button.
There are several patterns for candy costs regarding the number of members of each Pokémon family.
- The most common patterns for evolution families:
- When Pokémon have only two stages of evolution in its family, a second form costs 50 candies to evolve from a first one.
- When Pokémon have three stages of evolution in its family, a second form costs 25 candies to evolve from a first one, and a third form costs 100 candies to evolve from second one.
- Patterns for evolution families which Baby Pokémon were added to:
- When Pokémon has Baby Pokémon introduced that makes its one-stage Pokémon family a two-stage one. A second form costs 50 candies to evolve from a first one (Baby Pokémon).
- When Pokémon has Baby Pokémon introduced that makes its two-stage Pokémon family a three-stage one. A second form costs 25 candies to evolve from a first one (Baby Pokémon) and third form costs 50 candies to evolve from a second one.
- Patterns for evolution family of the most common Pokémon:
- When Pokémon is part of two-stage evolution family, a second form costs 25 candies to evolve from a first one.
- When Pokémon is part of three-stage evolution family, a second form costs 12 candies to evolve from a first one, and a third form costs 50 candies to evolve from a second one.
- Patterns for special evolution family:
- Being a part of two stage Pokémon families, Magikarp, Swablu, Wailmer, Meltan, and Noibat needs 400 candies each to evolve into Gyarados, Altaria, Wailord, Melmetal, and Noivern respectively.
- Being a part of two stage Pokémon family, Feebas requires 100 candies to evolve into Milotic.
- It also requires a 20km walked as Buddy Pokémon for its evolution.
There are several Pokémon that requires special Evolution Items to evolve. There currently seven Evolution Items: Dragon Scale, King's Rock, Metal Coat, Sun Stone, Up-Grade, Sinnoh Stone and Unova Stone. It is always just one evolution item required to perform singular evolution.
There are currently in game six Pokémon that need certain distance walked as Buddy Pokémon to be evolved.
- Eevee requires 10 km walked as Buddy Pokémon to evolve into either Espeon or Umbreon.
- Espeon evolves from Eevee only when evolution is performed at day.
- Umbreon evolves from Eevee only when evolution is performed at night.
- Feebas requires 20 km walked as Buddy Pokémon to evolve into Milotic.
- Mime Jr., Bonsly, and Happiny all require 15 km to be walked as a Buddy Pokemon to evolve into Mr. Mime, Sudowoodo, and Chansey respectively.
- Woobat requires 1 km walked as Buddy Pokémon to evolve into Swoobat.
There are also other evolution requirements to perform with Buddy Pokémon rather than walking distance.
- Galarian Farfetch'd requires making 10 Excellent Throws.
- Galarian Yamask requires winning 10 raids.
- Pancham requires catching 32 Dark-type Pokémon.
- Spritzee requires using 1 Incense-type item (including Mysterious Box)
- Swirlix requires being fed 25 treats.
- Eevee evolving into Sylveon requires earning 70 hearts (equivalent to reaching Great Buddy from zero hearts).
- Galarian Slowpoke evolving into Galarian Slowking requires catching 30 Psychic-type Pokémon.
- Galarian Slowpoke evolving into Galarian Slowbro requires catching 30 Poison-type Pokémon.
- Tyrantrum evolves from Tyrunt only when evolution is performed at day.
- Aurorus evolves from Amaura only when evolution is performed at night.
- Inkay requires the mobile device to be turned upside down.
- Glacial Lure Module allows Eevee to evolve into Glaceon.
- Magnetic Lure Module allows Magneton and Nosepass to evolve into Magnezone and Probopass respectively.
- Mossy Lure Module allows Eevee to evolve into Leafeon.
- Rainy Lure Module allows Sliggoo to evolve into Goodra.
- Sliggoo can also evolve anywhere with Rainy Weather without needing a Rainy Lure Module.
- Kadabra to Alakazam
- Machoke to Machamp
- Graveler to Golem (including Alolan form)
- Haunter to Gengar
- Boldore to Gigalith
- Gurdurr to Conkeldurr
- Karrablast to Escavalier
- Shelmet to Accelgor
Trading lower evolution (e.g.Machop) first also applies to this benefit.
- Main article: List of Pokémon families
Each Pokémon is a member of a Pokémon family (also known as evolutionary line). It is basically a group of Pokémon that are related with each other as one of such Pokémon evolve into or from another.
Pokémon evolution families can range between a single to three-stage evolutions, but there can also be more than three members within a family, as some of Pokémon families might be branched.
- Main article: Mega Evolution
Mega Evolution was announced and released in 2020. It is a temporary form change requiring Mega Energy. Pokémon are more powerful when Mega-Evolved.
- On the official support page for the Pokémon GO, Deepsea Scale and Deepsea Tooth used to be mentioned.
- It was also stated there that Feebas would be required to be walked a minimum of 20 km as Buddy Pokémon, before it had been released to the gameplay. 
- Searching the phrase "evolve" in Pokémon collection search return the list of all Pokémon with enough amount of candies to be evolved.
- Every Pokémon gives back 1 of its candy type when evolved. So for example, if a player has 23 Pidgey candies and 2 Pidgey (which need 12 candies to be evolved) they can evolve both of them, as the first one gives back 1 candy and then the player still has 12 remaining. After evolving both Pidgey, there will still be 1 candy remaining.
- Pokémon can be evolved at any health, even when fainted. After evolving, the new Pokémon would be at full health.
- Trade Evolution and more Pokémon originally discovered in Unova are here! Pokémon GO Live. Retrieved on 2020-01-10.
- PokemonGoApp. In 2020, Mega Evolution will be coming to Pokémon GO! You can look forward to meeting Mega-Evolved Pokémon in the real world!. Twitter. Retrieved on 2020-06-17.
- Evolving your Pokémon. Pokémon GO Support. Retrieved on 2017-14-12.