Here is the full list of all 15 PARTY RUSH!! achievements.
Completed Chapter 1.
Completed Chapter 15.
Completed Chapter 18.
Completed Chapter 20.
Acquired 50 characters.
Acquired 100 characters.
Summoned a legendary character using the Fragment of the World.
Walked 10,000 steps.
Completed the 30th Challenge.
Used a combined skill for the first time.
Came to Papaverine's Store and talked to the vendor for the first time.
Let Bunny make the Angelic Dress and used it in a battle.
Used Dragora's skill, "Please Eat Me!!"