Where to Find Seel

Generation 1

Red

Seafoam Islands

Trade Ponyta at the Pokémon Lab on Cinnabar Island

Blue

Seafoam Islands

Trade Ponyta at the Pokémon Lab on Cinnabar Island

Yellow

Seafoam Islands

Generation 2

Gold

Whirl Islands

Silver

Whirl Islands

Crystal

Whirl Islands (Morning & Day)

Generation 3

Ruby
Sapphire
Emerald
Fire Red

Seafoam Islands, Icefall Cave

Trade Ponyta at the Pokémon Lab on Cinnabar Island

Leaf Green

Seafoam Islands, Icefall Cave

Trade Ponyta at the Pokémon Lab on Cinnabar Island

Generation 4

Diamond

Routes 226 and 230

Pearl
Platinum

Breed Dewgong

Heart Gold

Route 47, Whirl Islands, Seafoam Islands

Soul Silver

Route 47, Whirl Islands, Seafoam Islands

Generation 5

Black

Giant Chasm (Surfing)

White

Giant Chasm (Surfing)

Black 2

Seaside Cave and Giant Chasm (Surfing)

White 2

Seaside Cave and Giant Chasm (Surfing)

Generation 6

X

Breed Dewgong

Y

Breed Dewgong

Omega Ruby

Route 125 (hidden Pokémon)

Alpha Sapphire

Route 125 (hidden Pokémon)

Generation 7

Sun
Moon
Ultra Sun

Seaward Cave (Surfing)

Poké Pelago

Ultra Moon

Seaward Cave (Surfing)

Poké Pelago

Let's Go Pikachu

Seafoam Islands

Let's Go Eevee

Seafoam Islands

Generation 8

Sword
Shield
Brilliant Diamond

Routes 226 and 230

Grand Underground – Fountainspring Cave, Whiteout Cave, Icy Cave, Glacial Cavern (After obtaining the National Pokédex)

Shining Pearl
Legends Arceus

Generation 9

Scarlet

The Hidden Treasures of Area Zero DLC:

Polar Biome

Tera Raid Battles (2★)

Violet

The Hidden Treasures of Area Zero DLC:

Polar Biome

Tera Raid Battles (2★)

Seel Evolution Tree