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