The complete Pokemon RBY pokedex, part 6

Pokémon Name: Mankey
Type: Fighting
Classification: Pig Monkey Pokemon
Pokédex Number: 056
Ability: Vital Spirit and Anger Nerve
Dream World ability: Defiant
Useful Attacks: Karate Chop
Location Found:
D/P/P: Route 225 and Route 226 (Poke Radar)
HG: Routes 9 and 42
SS: Trade with D/P/P/HG
B/W: Route 15 (swarm)

The first true Fighting-type Pokemon of the Kanto region. Its evolution is a bit more useful, though both suffer from weak stats outside of attack. These two have focused so much on rage that their other senses have withered over the years. Well, that's one possibility anyway.

Evolution: To Primeape at 28