Here is the full list of all 23 Swapperoo achievements.
Complete Stage S
Complete Stage P
Complete Stage M
Match 3 skulls at once
Complete Stage J
Complete Stage G
Match a skull with 1 move remaining
Match 6 tiles of the same color
Match 250 tiles total
Match 2 stars at once
Stop the music
Complete Stage D
Match 8 tiles at once
Complete Stage V
Complete Normal Mode
Complete Hard Mode
Complete Challenges 1
Complete Challenges 2
Match 3 padlocks at once
Drill 10 giant eyes in total
Match 5000 tiles total
Align 5 arrows of the same direction in a row
Detonate a poisonous skull