Here is the full list of all 31 Rhythm Sprout: Sick Beats & Bad Sweets achievements.
Defeat Count Arelle.
Fall through Count Arelle's trap door.
Cleared the first level.
Got all achievements in Rhythm Sprout!
Defeat Candy Mama.
"Defeat" King Sugar Daddy.
Defeat K-FLOW.
Defeat The Power Peppers.
Defeat Mrs. Chili.
Finish the Main Story.
Finish the Side Story.
Clear All Bonus Levels.
Clear 10 Levels in Turbo Mode.
Clear 5 Levels in Random Mode.
Clear 5 Levels in Mirror Mode.
Get 50 Stars.
Get 100 Stars.
Get your first CD.
Get 10 CDs.
Get 25 CDs.
Hit 20 Trap Notes in one level.
Listen to the same loop over and over again.
Die several times in a row.
Get one of the Target Scores in any level (no more, no less).
Get to the finish line with every unlockable skin.
Wear an unlockable skin for multiple levels.
Rewatched a cutscene multiple times.
Answered YES on every question at least once.
Answered NO on every question at least once.
Be very interested in Sugar Daddy's story.
Your love of trap doors knows no bounds.