Here is the full list of all 16 Masky achievements.
get Candycox mask
get Woodorn mask
get Wetto mask
get Catalis mask
Win 10 multiplayer battles / dances
Win 30 multiplayer battles / dances
Win 100 multiplayer battles / dances
Dance for a total of one hour
Dance for a total of five hours
Dance for a total of 24 hours
get Hospitalion mask
get Laboratous mask
get Cosmoid mask
get Graven mask
get Traino mask
get Hellatin mask