Here is the full list of all 19 Ben and Ed achievements.
Collect 100% of all candymeat.
Kill 100 chicken.
Beat all level unharmed.
Impress 1100 viewers.
Impress 700 viewers.
Kill 50 chicken.
Impress 200 viewers.
Beat 12 level unharmed.
Kill 20 chicken.
Finish the game.
Reunite with your friend.
Beat Hans.
Collect 50% of all candymeat.
Beat Hans' second masterpiece.
Collect 20% of all candymeat.
Beat 5 level unharmed.
Beat Hans' first masterpiece.
Reach a checkpoint in one piece.
Finish the tutorial.