The complete Pokemon RBY pokedex, part 9

Pokémon Name: Kingler
Type: Water
Classification: Pincer Pokemon
Pokédex Number: 099
Ability: Hyper Cutter and Shell Armor
Dream World ability: Sheer Force
Useful Attacks: Crabhammer
Location Found:
D/P/P: Evolve from Krabby
HG/SS: Cliff Cave
B/W: Route 4, Driftveil City, Route 13 (all via Fishing, bubble spots only, rare)

Both Krabby and Kingler have access to the ultra-destructive Crabhammer move, but you might want to save it for Kingler - its increased attack power makes the move even more deadly.

Evolution: From Krabby at 28