Costume Kingdom

This trophy will unlock when you've completed the first Apex. The portal to the Apex is located on the right side of the street in the first area and will cost 450 candies to unlock. There will be a few Goon fights to get through before you go up against Sky, the reigning Champion of Apex 1. All of his Hallowmon are level 10 so it's highly recommended you spend a few minutes spawning random battles to get your two Hallowmon up to level 10 (if you're not already there, of course). You can go up against him at level 8-9 but having that third level-10 ability will help you tremendously so it's best to just get to 10 before going up against him.

Once you've defeated him, interact with the portal just past where the battle took place and the trophy will unlock. You’ll also unlock the Tortoros Costume/Hallowmon. Interact with the second portal to accept the Quest to complete Apex 2 and when you go back to the open world, the second town area will now be available for exploration/completion.