Here is the full list of all 40 Shantae and the Seven Sirens achievements.
Collect all Monster Cards.
Upgrade all magic to max.
Complete the adventure as quickly as possible!
Complete the adventure with 100% completion as quickly as possible!
Complete the game in Beginner or Definitive Mode.
Complete the adventure with 100% completion!
Complete the game without any Health upgrades and all Heart Squids collected.
Unearthed all secrets.
Open all Shock Machines.
Avoid startling the Lobster Girl throughout the adventure.
Witness every magical outcome with Slimes.
Complete the adventure!
Complete the game in Rule Breaker or Full Deck Mode.
Defeated the Empress Siren.
Win the highest total in a Hula Contest.
Deactivate all the Towers.
Defeated the fifth Siren.
Shock a circus squid.
Obtain all magical forms.
Complete a Ghostly Quest.
Unearth a buried treasure.
Learn all magical dances.
Defeated the fourth Siren.
Revitalize cellular functions.
Locate the sunken ship remains.
Fell for a double cross.
Open a Shock Machine.
Ascend to Armor Town.
Defeated the third Siren.
Turn an enemy to an ally by helping them heal.
Enter the Sea Lab.
Obtain the Lucky Amulet.
Defeated the second Siren.
Use the valve.
Uncovered a possible threat.
Reach Tree Town.
Have three Monster Cards equipped at once.
Defeated the first Siren.
Took the tour!
Obtain a Monster Card.