Clamp is learned by 5 species by level

Effect, in PokéAPI's words

“Prevents the target from fleeing and inflicts damage for 2-5 turns.”

Who learns it

5 species in all, 8 of 21 games shown

Let's Go Pikachu and Let's Go Eevee: 1 species

Species	Method	Level
Shellder	Level up	22

Ultra Sun and Ultra Moon: 4 species

Species	Method	Level
Clamperl	Level up	1
Binacle	Level up	20
Barbaracle	Level up	20
Shellder	Level up	25

Sun and Moon: 4 species

Species	Method	Level
Clamperl	Level up	1
Binacle	Level up	20
Barbaracle	Level up	20
Shellder	Level up	25

Omega Ruby and Alpha Sapphire: 4 species

Species	Method	Level
Clamperl	Level up	1
Binacle	Level up	20
Barbaracle	Level up	20
Shellder	Level up	25

X and Y: 4 species

Species	Method	Level
Clamperl	Level up	1
Binacle	Level up	20
Barbaracle	Level up	20
Shellder	Level up	25

Black 2 and White 2: 2 species

Species	Method	Level
Clamperl	Level up	1
Shellder	Level up	25

Black and White: 2 species

Species	Method	Level
Clamperl	Level up	1
Shellder	Level up	25

HeartGold and SoulSilver: 2 species

Species	Method	Level
Clamperl	Level up	1
Shellder	Level up	25

Changed over time

2 changes since Generation I

1. Through Gen IVAccuracy 75%85% from Black and White, Generation V
2. Through Gen IVPP 1015 from Black and White, Generation V