Here is the full list of all 12 Scary Girl achievements.
Achieve a perfect status on every level.
Make the tough choice when confronted by Dr. Maybee.
Purchase all the shop items.
Triumph over the dangers deep beneath the sea.
Prove your worth to Chihoohoo in a rumble with his guards.
Force your way through Warmachine to get into Bad City.
Survive Momma Yeti's cave-in.
Start a Co-op game.
Collect a full heart container.
Catch an Umbrella Seed to the Old Man Mountains.
Purchase a store item.
Complete a Dojo training session.