Here is the full list of all 9 The Haunting of Billy achievements.
Wear a full costume set.
Look at that lil' devil!
Meet your loving and caring guardian demon.
Find your way off the level.
Blow an enemy clean off the level.
Don't take Bucky with you.
Have on you 250 candy at one time.
Wear a full costume where every piece is unique.
Find and equip Bucky's pan.