Here is the full list of all 11 TouHou Pants Contest achievements.
All CG Successfully collected
Collected the One hundred pants
Complete all of the main event
Complete the battle at 0 frames
Failure ten times
Defeat furan for the first time
Collected the ten pants
Defeat yuyuko for the first time
Failure one times
Defeat kaguya for the first time
Collected the first pants