Here is the full list of all 12 Shank achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Complete Co-op Campaign Mode
Complete Single Player Campaign on Hard Mode
Take out 1000 enemies
Complete Single Player Campaign on Normal Mode
Defeat Cesar
Defeat The Priest
Defeat Cassandra
Defeat The Butcher
100 Chainsaw kills
Take out 100 enemies
Defeat El Raton
Take out 20 enemies