Here is the full list of all 25 Hotel Transylvania 3: Monsters Overboard trophies - there are 7 bronze, 10 silver, 7 gold and 1 platinum.
Congratulations! You’ve done all there is to do in Hotel Transylvania 3: Monsters Overboard!
Hit an enemy with a ricocheted Mummimpa.
Defeat any enemy other than a Feeble Flower with nothing but a single Wolfimpa.
Defeat a Coconut Crab while it’s stunned.
Have 30 Vampimpa at once for more than 5 seconds
Defeat the Dastardly Dragon and retrieve the final part of Neptune’s Compass
Unlock every single Impa Portal.
Collected every single Treasure hidden in the Lost Islands.
Collect half of the Treasures hidden in the Lost Islands.
Have 5 of each Impa type at once for more than 5 seconds
Use Mummimpa’s Magic Sand to block the smell trail from a Stinkbulb.
Rescued Murray.
Defeat the Cruel Crustacean and retrieve the second part of Neptune’s Compass
You’ve successfully liberated 3 objects from Giant Clams.
Defeat an enemy with the impact from a thrown Frankenimpa.
Rescued Frankenstein.
Unlock half of all Impa Portals.
Defeat the Fiendish Flower and retrieve the first part of Neptune’s Compass.
You’ve collected the first of many treasures.
You’ve defeated 5 enemies in a single night.
You’ve safely retrieved an object from an angry Giant Clam.
Rescued Wayne.
Unlock the third Impa Portal.
Collect 5 Imparite stones in a single night.
Complete the tutorial and meet up with Ericka.