Here is the full list of all 19 PJ Masks Power Heroes: Mighty Alliance achievements.
Defeat Luna Girl and her moths
Defeat Night Ninja and his Ninjalinos
Defeat Romeo and his robots
Defeat the evil alliance
Find one hero’s mask
Find all hero’s masks
Find a collectible
Find all collectibles
Find all gems, masks and collectibles in a level
Collect 6500 gems
Defeat an enemy of each type
Disperse 50 moths
Defeat 25 Ninjalinos
Defeat 25 Robots
Jump on top of 20 enemies
Break 350 boxes
Go through 50 accelerators
Discover a secret area
Discover 10 secret areas