Where to Find Oshawott

Generation 1

Red
Blue
Yellow

Generation 2

Gold
Silver
Crystal

Generation 3

Ruby
Sapphire
Emerald
Fire Red
Leaf Green

Generation 4

Diamond
Pearl
Platinum
Heart Gold
Soul Silver

Generation 5

Black

Nuvema Town: Choose as Starter Pokemon

White

Nuvema Town: Choose as Starter Pokemon

Black 2

Nuvema Town: Choose as Starter Pokemon

White 2

Nuvema Town: Choose as Starter Pokemon

Generation 6

X
Y
Omega Ruby

Received from Professor Birch on Route 101 after completing the Delta Episode

Alpha Sapphire

Received from Professor Birch on Route 101 after completing the Delta Episode

Generation 7

Sun

Breed Samurott

Moon

Breed Samurott

Ultra Sun
Ultra Moon
Let's Go Pikachu
Let's Go Eevee

Generation 8

Sword
Shield
Brilliant Diamond
Shining Pearl
Legends Arceus

Jubilife Village: First partner Pokémon from Professor Laventon, Received from Professor Laventon (after completing Mission 18, if the player did not choose Oshawott)

Alabaster Icelands: (Space-time distortions (after completing Mission 18), massive mass outbreaks after completing Request 102)

Generation 9

Scarlet

The Hidden Treasures of Area Zero DLC:

Polar Biome (after boosting biodiversity in the Polar Biome)

Violet

The Hidden Treasures of Area Zero DLC:

Polar Biome (after boosting biodiversity in the Polar Biome)

Oshawott Evolution Tree

Level 17

Level 36

Level up in Hisui for Hisuian Samurott