Here is the full list of all 19 Juju achievements.
Complete a level in co-op.
Complete any level without collecting an amber.
Defeat Calypso.
Complete all unlockable levels.
Defeat Cobos and collect his key part.
Gather every Coin in the game.
Find all secret teleports.
Unlock all skills.
Complete one unlockable level.
Defeat Octobos and collect his key part.
Make 4 enemies dance at once.
Defeat Robos and collect his key part.
Complete any level without losing a heart.
Defeat Frobos and collect his key part.
Unlock a new skill.
Find a secret teleport.
Collect more than 100% of ambers in any level.
Hit 3 enemies with one dash.
Gather all Coins on one level.