Here is the full list of all 20 Suli Fallen Harmony achievements.
Tickle Suli three times in a row
Take the dog to your house
Harass Archibaldus
Try to knock the people of Harmony with the plank
Discover Nautilia
Take a look to the sea products
Those crow's eyes are following me...
Try to offer your pearls to queen Bala-Bala
Make gas sounds with the balloonfish
Speak with all the spirits
Understand Jean-Pierre without making any mistake
Careful ! The three headed monkey !
Speak with all of the angry villagers
Only pick up the good plants
Finish the potion correctly the first time
Don't ever use the map
Play Juba's melody
Try to combine all the objects with Suli
Defeat the invocation without getting hit
Unlock all of the trophies