Do I have to put them up again because it doesn't look like it's working even after getting the dungeon oh wait do I have to talk to Cloe 1st?
Viewing post in Corrupted Kingdoms (NSFW 18+) comments
For Pixie you don't need the dungeon, just put up the decorations and sleep a few nights.
For Gwen and Jessica you need the dungeon, check at night with the decorations on.
Chloe has a costume but it's not really halloween related.
You just check her room on a weekend after progressing her and Jessica's stories a little.