Here is the full list of all 8 Dude Cops achievements. It takes around 0-1 hour to unlock all of the achievements.
Teach Lil' Timmy a valuable lesson
Have a pleasant chat with a zombie
Remove the pesky mouse
Does Dracula wear boxers or briefs?
Help the Old Lady across the "street"
Rescue the lost ball
Examine the barrel
Save the cat from the tree