Evolution (Japanese: 進化) is the first evolution in the Pokémon franchise when one Pokémon, upon reaching a certain level, using certain stones, learning certain moves, or being traded, evolves into a different kind of Pokémon. In Pokémon Gold, Silver, Crystal, HeartGold and SoulSilver games, it is stated that Professor Elm is an expert on evolution, and discovered that Pikachu evolves from Pichu.
In the anime, during evolution, a Pokémon will become surrounded by a light and slowly change shape. From The Beginning through to Diamond and Pearl, the Pokémon is surrounded by a white light, while in Black & White to Sun & Moon, the Pokémon is surrounded by a golden or blue light. An evolution can also occur through multiple Pokémon of the same species combining.
To some Pokémon, evolution means growing up, while to others, it just refers becoming another species or getting upgraded. However, many of them retain the memories of their life during their pre-evolution form.
Normal Evolution tricks
Pokémon gain experience after battling wild Pokémon and Pokémon Trainers. The more experience a Pokémon gains, the more it levels up. When a Pokémon reaches a particular level, it will evolve into its next form (if it has one). This is very helpful to most Trainers who want their Pokémon to become stronger.
There are ways to share experience, such as allow a Pokémon you wish it to evolve to hold Exp. Share. It is a hold item that allows the user to earn experience even if it did not participate in the battle. This is a convenient tool if you want to level up a new or low-level Pokémon.
Evolution can be prevented by simply press the 'B' button on the Game when the Pokémon is attempting to evolve. This is useful as some Pokémon will learn moves that cannot be learnt in a later form or if you want a Pokémon to learn a move earlier than usual. For example, Gabite. If you let Gible evolve into Gabite at level 24 it will learn Dragon Rush at level 49, but if you keep Gible it will learn Dragon Rush at level 37. Sometimes it doesn't matter if you let it evolve or not. The Pokémon can hold an Everstone, which keeps them from evolving, so that you don't have to keep cancelling the evolution every time the Pokémon levels up. However, if your Pokémon has evolved, it might not evolve again (Raticate, Linoone, etc.) Although some Pokémon can evolve more than once (Poliwhirl, Cascoon, etc.), some basic Pokémon just can't evolve, due to undiscovered forms, or if they are really rare (Chatot, Groudon, etc.) There are also Pokémon that can evolve into different things like love, choice, etc. For example, Eevee, Poliwhirl, Wurmple, or Kirlia.
Special Condition Evolutions
Stone Evolutions
Some Pokémon will not evolve unless you use a special stones called Evolutionary Stones. These special Items are linked to the Pokémon's type. Here are a list of Pokémon that can evolve by giving them the stones.
Item Evolutions
Some items are needed for a Pokémon to evolve. If a Pokémon hold the item allowing it to evolve, let it level up once and it will then evolve into the second form.
| List of Pokémon that Evolve by Attached Items | ||
|---|---|---|
| Name | Conditions | Evolve to |
Gligar 
|
Held Item: Razor Fang at Night | Gliscor 
|
Sneasel 
|
Held Item: Razor Claw at Night | Weavile 
|
Happiny 
|
Held Item: Oval Stone at Day | Chansey 
|
Applin 
|
Held Item: Tart Apple. | Flapple 
|
| Held Item: Sweet Apple. | Appletun 
| |
Sinistea 
|
Held Item: Cracked Pot. | Polteageist 
|
| Sinistea (Rare Form)
|
Held Item: Chipped Pot. | Polteageist (Rare Form)
|
Trading Evolutions
A small group of Pokémon refuses to evolve, no matter if you are at the appropriate level to trigger the evolve process, unless you trade them with a friend. Some Pokémon need to have a held item to evolve when trading with a friend. Another group require specific Pokémon to be trade in order to evolve.
| Name | Conditions | Evolve to |
Kadabra 
|
None | Alakazam 
|
Haunter 
|
Gengar 
| |
Machoke 
|
Machamp 
| |
Graveler 
|
Golem 
| |
Graveler (Alolan) 
|
Golem (Alolan) 
| |
Boldore 
|
Gigalith 
| |
Gurdurr 
|
Conkeldurr 
| |
Phantump 
|
Trevenant 
| |
Pumpkaboo 
|
Gourgeist 
| |
Onix 
|
Held Item: Metal Coat | Steelix 
|
Scyther 
|
Scizor 
| |
Poliwhirl 
|
Held Item: King's Rock | Politoed 
|
Slowpoke 
|
Slowking 
| |
Seadra 
|
Held Item: Dragon Scale | Kingdra 
|
Porygon 
|
Held Item: Up-Grade | Porygon2 
|
Clamperl 
|
Held Item: Deepseascale | Gorebyss 
|
| Held Item: Deepseatooth | Huntail 
| |
Electabuzz 
|
Held Item: Electirizer | Electivire 
|
Magmar 
|
Held Item: Magmarizer | Magmortar 
|
Rhydon 
|
Held Item: Protector | Rhyperior 
|
| Porygon2
|
Held Item: Dubious Disc | Porygon-Z 
|
Feebas 
|
Held Item: Prism Scale (Generation V-) | Milotic 
|
Dusclops 
|
Held Item: Reaper Cloth | Dusknoir 
|
Shelmet 
|
Trade with Karrablast | Accelgor 
|
Karrablast 
|
Trade with Shelmet | Escavalier 
|
Spritzee 
|
Held Item: Sachet | Aromatisse 
|
Swirlix 
|
Held Item: Whipped Dream | Slurpuff 
|
Gender Evolution
Small groups of Pokémon requires a gender to evolve into the next stage.
| List of Pokémon that Evolve by Gender | ||
|---|---|---|
| Name | Conditions | Evolve to |
Burmy   File:412C.png
|
Level 20, (♀ - Female) | Wormadam   File:413C.png
|
| Level 20, (♂ - Male) | Mothim 
| |
Combee 
|
Level 25, (♀ - Female) | Vespiquen 
|
Snorunt 
|
Shiny Stone  , (♀ - Female)
|
Froslass 
|
Salandit 
|
Level 33, (♀ - Female) | Salazzle 
|
Friendship Evolutions
Certain Pokémon, especially baby Pokémon, requires friendship with its trainer and if they are fond enough, they are willing to evolve. Some Pokémon only evolves in a certain time of the day with friendship.
| List of Pokémon that Evolve by Friendship | ||
|---|---|---|
| Name | Conditions | Evolve to |
Golbat 
|
None | Crobat 
|
| Chansey
|
Blissey 
| |
Pichu 
|
Pikachu 
| |
Cleffa 
|
Clefairy 
| |
Igglybuff 
|
Jigglypuff 
| |
Togepi 
|
Togetic 
| |
Azurill 
|
Marill 
| |
Buneary 
|
Lopunny 
| |
Munchlax 
|
Snorlax 
| |
Woobat 
|
Swoobat 
| |
Swadloon 
|
Leavanny 
| |
Type: Null 
|
Silvally 
| |
Eevee 
|
at Day | Espeon 
|
Budew 
|
Roselia 
| |
Riolu 
|
Lucario 
| |
Meowth (Alolan) 
|
at Night | Persian (Alolan) 
|
| Eevee
|
Umbreon 
| |
Chingling 
|
Chimecho 
| |
Snom 
|
Frosmoth 
| |
Location Based Evolutions
Special Pokémon evolve at a certain area of location.
| List of Pokémon that Evolve by Locations | ||
|---|---|---|
| Name | Locations | Evolve to |
Magneton 
|
Mt. Coronet (Generation IV), Chargestone Cave (Generation V), Route 13 (Generation VI), Vast Poni Canyon (Generation VII) | Magnezone 
|
Nosepass 
|
Probopass 
| |
| Eevee
|
Moss Rock at Eterna Forest (Generation IV), Moss Rock at Pinwheel Forest (Generation V), Route 20 (Generation VI), Moss Rock at Lush Jungle (Generation VII) | Leafeon 
|
| Ice Rock at Route 217 (Generation IV), Ice Rock at Twist Mountain (Generation V), Frost Cavern (Generation VI), Ice Rock at Mount Lanakila (Generation VII) | Glaceon 
| |
Charjabug 
|
Vast Poni Canyon | Vikavolt 
|
Crabrawler 
|
atop Mount Lanakila | Crabominable 
|
Attack Based Evolutions
Certain Pokémon need to know a move to evolve. This method was introduced in Generation IV, starting with Diamond/Pearl/Platinum.
| List of Pokémon that Evolve by Learning Moves | ||
|---|---|---|
| Name | Conditions | Evolve to |
Tangela 
|
learning AncientPower | Tangrowth 
|
Yanma 
|
Yanmega 
| |
Piloswine 
|
Mamoswine 
| |
Bonsly 
|
learning Mimic | Sudowoodo 
|
Mime Jr. 
|
Mr. Mime 
| |
Lickitung 
|
learning Rollout | Lickilicky 
|
Aipom 
|
learning Double Hit | Ambipom 
|
Steenee 
|
learning Stomp | Tsareena 
|
Clobbopus 
|
learning Taunt | Grapploct 
|
Time Based Evolutions
The current time of day will sometimes affect evolution. This method was introduced in Generation VI, starting with X/Y/OR/AS.
| List of Pokémon that Evolve by Time | ||
|---|---|---|
| Name | Conditions | Evolve to |
Tyrunt 
|
Level 39+ during the day. | Tyrantrum 
|
Amaura 
|
Level 39+ during the night. | Aurorus 
|
Rattata (Alolan) 
|
Level 20+ during the night. | Raticate (Alolan) 
|
Cubone 
|
Level 28+ during the night. | Marowak (Alolan) 
|
Yungoos 
|
Level 20+ during the day. | Gumshoos 
|
Rockruff 
|
Level 25+ during the day. | Lycanroc (Sun) 
|
| Level 25+ during the night. | Lycanroc (Moon) 
| |
Fomantis 
|
Level 34+ during the day. | Lurantis 
|
Linoone (Galarian) 
|
Level 35+ at night. | Obstagoon 
|
Unique Evolutions
Some Pokémon have certain type of unique way of evolve.
| List of Pokémon that Evolve by Unique Way | ||
|---|---|---|
| Name | Conditions | Evolve to |
Farfetch'd (Galarian) 
|
Get 3 Critical Hits in 1 Battle | Sirfetch'd 
|
| Eevee
|
2+ Affection in Pokémon-Amie or Pokémon Refresh/Has high friendship, learn a  -type move.
|
Sylveon 
|
Wurmple 
|
Level 7 (Random depending on PV - Personality Value) | Silcoon 
|
Cascoon 
| ||
Tyrogue 
|
Level 20, Attack stats more than Defense | Hitmonlee 
|
| Level 20, Defense stats more than Attack | Hitmonchan 
| |
| Level 20, Attack stats equal to Defense | Hitmontop 
| |
| Feebas
|
Maxed out Beauty Condition and then level up (Generation III - IV) | Milotic
|
Nincada 
|
Level 20, with empty Poké Ball and an open slot on your party. | Shedinja 
|
Mantyke 
|
A Remoraid in your party and then level up. | Mantine 
|
Yamask (Galar) 
|
Walk under the stone bridge in Dusty Bowl after Yamask has taken at least 49 HP in damage without fainting. | Runerigus 
|
Pancham 
|
Level 32+ with a  -type in your party.
|
Pangoro 
|
Inkay 
|
Level 30+ while holding the Nintendo 3DS upside down/the Nintendo Switch upside down in handheld mode when disconnecting the Pro Controller by removing the Switch from the docking station. | Malamar 
|
Sliggoo 
|
Level 50+ in the rain. | Goodra 
|
Cosmoem 
|
Level 53+ in Pokémon Sun. | Solgaleo 
|
| Level 53+ in Pokémon Moon. | Lunala 
| |
Toxel 
|
Level 30+ with Bashful, Bold, Calm, Careful, Gentle, Lonely, Mild, Modest, Quiet, Relaxed, Serious, or Timid Nature. | Toxtricity (Low Key) File:849-Low.png |
| Level 30+ with Adamant, Brave, Docile, Hardy, Hasty, Impish, Jolly, Lax, Naive, Naughty, Rash, Quirky, or Sassy Nature. | Toxtricity (Amped) 
| |
Milcery 
|
Spin clockwise for 5 seconds during the day | Alcremie (Vanilla Cream) 
|
| Spin counter-clockwise for 5 seconds during the day | Alcremie (Ruby Cream)
| |
| Spin clockwise for 5 seconds during the night | Alcremie (Matcha Cream)
| |
| Spin counter-clockwise for 5 seconds during the night | Alcremie (Salted Cream)
| |
| Spin clockwise for more than 5 seconds during the day | Alcremie (Caramel Swirl)
| |
| Spin counter-clockwise for more than 5 seconds during the day | Alcremie (Ruby Swirl)
| |
| Spin clockwise for more than 5 seconds during the night | Alcremie (Lemon Cream)
| |
| Spin counter-clockwise for more than 5 seconds during the night | Alcremie (Mint Cream)
| |
| Spin counter-clockwise for more than 10 seconds during the dusk/dawn | Alcremie (Rainbow Cream)
| |
Mega Stone Evolutions
Certain Pokémon will be able to evolve into a Mega form, the final form for one-evolution families and second/true final form for two-evolution families with the use of a Mega Stone, a held object. However this evolution will devolve back into their previous form at the end of the battle.
Bond Phenomenon
There's a special evolution that Ash's Greninja can do due to his strong bond with Ash called Ash-Greninja, that was later described as Bond Phenomenon.
| List of Pokémon with Bond Phenomenon | ||
|---|---|---|
| Name | Conditions | Evolve to |
 Greninja (Battle Bond)
|
after defeating a Pokémon |  Ash-Greninja
|
Devolution
Primal Reversion
Primal Reversion is a similar state to Mega Evolution, but the Pokémon devolve to a previous state in the past.
It is a possible game mechanic in Pokémon Omega Ruby & Alpha Sapphire, most likely because this mechanic was founded during development of Pokémon Omega Ruby & Alpha Sapphire.
Other
Devolution is a form of reverse evolution when a Pokemon reverts to a previous state. The only instance devolution happens in the games is in Pokémon Super Mystery Dungeon, in which the player Pokémon and partner Pokémon evolve and soon devolve three times during the main story, and Pokémon Mystery Dungeon: Gates to Infinity, which includes the Devolve Orb that devolves all enemies in the room.
Devolution is common in the Manga and TCG. It is achieved mainly unnaturally - through experimentation, or Devolution Spray. Though certain Pokemon, such as Isamu's Clefairy and Pikachu are capable of devolving themselves. The TCG also has it that Eeveelutions can revert into Eevee and that Mew has two special attacks named the Devolution Beam and Devo Crush - both of which which devolves the Pokemon hit by the attack. Golurk and Jirachi also possess special attacks which allow them to devolve an opposing Pokemon.
Anime
In the Anime Episode, Electric Shock Showdown, Misty points out that once Pikachu evolves with the use of the Thunder Stone, Pikachu won't revert back.
In An Epic Defense Force, Luke's Golett seemingly evolves to Golurk in a Movie then Devolves back to Golett, repairing the Golurk Statue, as it turns out to be fictitious.
Another instance of the non-existence of Devolution, is when Bonnie requested Ash's Frogadier to devolve back to Froakie, Clemont said that it would be impossible.
In relation to reality
Evolution is more similar to metamorphosis (the process certain bugs undergo to become an adult) than actual evolution(a long process that happens to populations of creatures).
Trivia
- There are eight Pokémon that can evolve into two different Pokémon, but only two that evolve into more: Tyrogue and Eevee.
- As of Generation VII, there are sixty-six Pokémon that do not evolve in any way. This is discounting the fifty-six Legendary Pokémon and seventeen Mythical Pokémon.
- In Dream a Little Dream from Me!, there is a group of Pokémon who evolved and devolved unnaturally, one actually missing its second evolved form.
- In Final Rivals!, an evolution has occurred through multiple Pokémon of the same species combining, which was shown by Ash's Meltan and its horde.
- Larvesta evolves at the highest level out of all unevolved pokemon so far(lvl 59).
- Zweilous evolves at the highest level out of any evolved pokemon so far(lvl64).
- Porygon is currently the only Pokemon to be able to evolve at level 1 into both its evolutions, as they do not need a certain level to evolve.
- Feebas is currently the only Pokemon who had its evolution method changed. This was because the beauty condition was removed from Generation V onwards, therefore rendering it impossible to evolve a Feebas into Milotic by that method, hence the Prism scale was introduced.