Region-based Evolution

Region-based Evolution refers to Pokémon that evolve in a certain region in the Pokémon games. This method of Evolution was introduced in Generation VII.

All known region-based Evolutions are branched Evolutions, in which a Pokémon evolves into a regional form of a previously introduced Pokémon.

List of region-based Evolutions

Previous Evolution		Region-based Evolution			Later Evolution
Introduced in Generation VII
Pichu Electric	+ Level up with high friendship →	Pikachu Electric	+ Thunder Stone in Alola →	Alolan Raichu Electric Psychic	Alolan Raichu does not evolve
Exeggcute is the lowest in its line		Exeggcute Grass Psychic	+ Leaf Stone in Alola →	Alolan Exeggutor Grass Dragon	Alolan Exeggutor does not evolve
Cubone is the lowest in its line		Cubone Ground	+ Level 28+ in Alola →	Alolan Marowak Fire Ghost	Alolan Marowak does not evolve
Introduced in Generation VIII (Pokémon Sword and Shield)
Koffing is the lowest in its line		Koffing Poison	+ Level 35+ in Galar →	Galarian Weezing Poison Fairy	Galarian Weezing does not evolve
Mime Jr. is the lowest in its line		Mime Jr. Psychic Fairy	+ + Level up knowing Mimic in Galar →	Galarian Mr. Mime Ice Psychic	Level 42+ in Galar →	Mr. Rime Ice Psychic
Introduced in Generation VIII (Pokémon Legends: Arceus)
Cyndaquil Fire	+ Level 17+ in Hisui →	Quilava Fire	+ Level 36+ in Hisui →	Hisuian Typhlosion Fire Ghost	Hisuian Typhlosion does not evolve
Oshawott Water	Level 17+ →	Dewott Water	+ Level 36+ in Hisui →	Hisuian Samurott Water Dark	Hisuian Samurott does not evolve
Petilil is the lowest in its line		Petilil Grass	+ Sun Stone in Hisui →	Hisuian Lilligant Grass Fighting	Hisuian Lilligant does not evolve
Rufflet is the lowest in its line		Rufflet Normal Flying	+ Level 54+ in Hisui →	Hisuian Braviary Psychic Flying	Hisuian Braviary does not evolve
Goomy is the lowest in its line		Goomy Dragon	+ Level 40+ in Hisui →	Hisuian Sliggoo Steel Dragon	+ Level 50+ during rain →	Hisuian Goodra Steel Dragon
Bergmite is the lowest in its line		Bergmite Ice	+ Level 37+ in Hisui →	Hisuian Avalugg Ice Rock	Hisuian Avalugg does not evolve
Rowlet Grass Flying	Level 17+ →	Dartrix Grass Flying	+ Level 36+ in Hisui →	Hisuian Decidueye Grass Fighting	Hisuian Decidueye does not evolve

List of other evolutionary branches

These are their evolutionary branches other than region-based Evolutions.

Previous Evolution		Evolution			Later Evolution
Introduced in Generation I
Pichu Electric	+ Level up with high friendship →	Pikachu Electric	Thunder Stone →	Raichu Electric	Raichu does not evolve
Exeggcute is the lowest in its line		Exeggcute Grass Psychic	Leaf Stone →	Exeggutor Grass Psychic	Exeggutor does not evolve
Cubone is the lowest in its line		Cubone Ground	Level 28+ →	Marowak Ground	Marowak does not evolve
Koffing is the lowest in its line		Koffing Poison	Level 35+ →	Weezing Poison	Weezing does not evolve
Introduced in Generation II
Cyndaquil Fire	Level 14+ →	Quilava Fire	Level 36+ →	Typhlosion Fire	Typhlosion does not evolve
Introduced in Generation IV
Mime Jr. is the lowest in its line		Mime Jr. Psychic Fairy	+ Level up knowing Mimic →	Mr. Mime Psychic Fairy	Mr. Mime does not evolve
Introduced in Generation V
Oshawott Water	Level 17+ →	Dewott Water	Level 36+ →	Samurott Water	Samurott does not evolve
Petilil is the lowest in its line		Petilil Grass	Sun Stone →	Lilligant Grass	Lilligant does not evolve
Rufflet is the lowest in its line		Rufflet Normal Flying	Level 54+ →	Braviary Normal Flying	Braviary does not evolve
Introduced in Generation VI
Goomy is the lowest in its line		Goomy Dragon	Level 40+ →	Sliggoo Dragon	+ Level 50+ during rain →	Goodra Dragon
Bergmite is the lowest in its line		Bergmite Ice	Level 37+ →	Avalugg Ice	Avalugg does not evolve
Introduced in Generation VII
Rowlet Grass Flying	Level 17+ →	Dartrix Grass Flying	Level 34+ →	Decidueye Grass Ghost	Decidueye does not evolve

In the core series games

A region-based Evolution is triggered once the Pokémon levels up in a certain region, either at the end of a Pokémon battle or by the use of a Rare Candy.

In Pokémon Ultra Sun and Ultra Moon, if a Pikachu, Cubone, or Exeggcute evolves in Ultra Space, it will become a Kantonian Raichu, Marowak, or Exeggutor rather than their respective Alolan forms. They still evolve into their Kantonian forms even in the Ultra Ruin, which is a parallel version of Alola identified as part of the Ultra Space.

In the TCG

In the Pokémon Trading Card Game, those evolved Pokémon are simply available as regular Evolutions with no additional requirement. For instance, a Pikachu card can equally evolve into a Raichu or Alolan Raichu card.

Trivia

Dartrix is the only Pokémon whose original Evolution and region-based Evolution are triggered under different circumstances other than the current region. Specifically, it evolves into Decidueye or Hisuian Decidueye at different levels.
In the Pokémon Diamond and Pearl demo, Professor Rowan says this if the player shows him a Roselia: "You have the Thorn Pokémon ROSELIA. Some Pokémon that haven't evolved in other regions might evolve here in the Sinnoh region." This may have implied at the time that Roselia evolves into Roserade only in Sinnoh, but it can actually evolve using a Shiny Stone regardless of region.

Pokémon types

All region-based Evolutions have two types.
- Cubone is the only Pokémon that does not share any type with its region-based Evolution. Specifically, Cubone is Ground-type while Alolan Marowak is Fire/Ghost.
- With the exception of Cubone, if the pre-Evolution had a single type, the region-based Evolution keeps this type and gains a new one. For instance, Pikachu is Electric-type while Alolan Raichu is Electric/Psychic.
- If the pre-Evolution had two types, the region-based Evolution keeps one of them while replacing the other type with another. For instance, Mime Jr. is Psychic/Fairy while Galarian Mr. Mime is Ice/Psychic.
Grass is the type shared by most region-based Evolutions, with 3 Pokémon having it as part of their type combinations: Alolan Exeggutor (Grass/Dragon), Hisuian Lilligant (Grass/Fighting), and Hisuian Decidueye (Grass/Fighting).
- Grass/Fighting is the only type combination shared by two region-based Evolutions.
Out of all Pokémon with region-based Evolutions, Dartrix is the only one that does not have the same type combination as its original Evolution. Specifically, Dartrix is Grass/Flying while Decidueye is Grass/Ghost.

Origins of region-based Evolutions

Some Pokédex entries mention the origins of the region-based Evolutions:

Alola's weather,^[1] climate,^[1] and food^[1]^[2] are some causes of Pikachu evolving into Alolan Raichu.
Alola's strong sunlight awakened the true power of Alolan Exeggutor.^[3]^[4]

References

↑ ^1.0 ^1.1 ^1.2 "It's believed that the weather, climate, and food of the Alola region all play a part in causing Pikachu to evolve into this form of Raichu." - Alolan Raichu's Pokédex entry in Pokémon Sword
↑ "It only evolves to this form in the Alola region. According to researchers, its diet is one of the causes of this change." - Alolan Raichu's Pokédex entry in Pokémon Sun
↑ "The strong sunlight of the Alola region has awakened the power hidden within Exeggcute. This is the result." - Alolan Exeggutor's Pokédex entry in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!
↑ "Blazing sunlight has brought out the true form and powers of this Pokémon." - Alolan Exeggutor's Pokédex entry in Pokémon Sword