Here is the full list of all 22 Boo Party achievements.
Jump 100 hurdles!
Complete the Cherry Run
Complete Time Attack in less than 60 minutes
Collect 120 Sewer Diamonds
Complete a dance without missing a step
Get the secret photo
Clear the game
Pet all the cats
Get the Scientist's photo
Get the Bakeneko's photo
Get the Slasher's photo
Get the Witch's photo
Get the Aliens' photo
Get Frankie's photo
Get Medusa's photo
Get the Mermaid's photo
Get the Plant Lady's photo
Get the Mummy's photo
Complete Succu-Bouncer in single-player
Get the Werewolf's photo
Get the Demon's photo
Get the Vampire's photo