Full list of all 18 Costume Quest 2 achievements worth 1,000 gamerscore. It takes around 8-10 hours to unlock all of the achievements on Xbox One.
Restored the timeline to save Halloween
Got the liberty kids to bust a move
Mastered all combat techniques from Corvus
Bashed 10 Monster Patrols
Defeated Ophirion
Used the Pterodactyl Costume to flap 10 flappy things
Upgraded 3 costumes
Collected over 4 thousand candies
Tried on 5 different costumes
Defeated Kronoculus and his Kronys
Collect all Creepy Treat Cards
Find the Wolfman
Find the Solar System
Complete all quests in the game
Use every costume special in combat
Try every Creepy Treat Card in combat
Finish the game having fought every battle with Candy Corn in your party
Use the clown horn 1000 times