Paper Mario: Sticker Star doesn’t have a lot of secrets and most of the stuff is pretty irrelevant gameplay wise but we’re completionists after all and we’ll help you uncover every secret available in the game.
After completing World 1-6, the Goomba Fortress, the Sticker Fest grounds in Decalburg will start becoming clean again. You’ll see eight flags in the middle with each one of them representing a specific challenge to complete inside the game: once the challemnge has completed the flag will be closed.
Some of them may require some work, like finding all Hp hearts and all Blue Doors but our two guides will make that task a little easier to manage. Most of the others you’ll get by simply playing through the game; getting a perfect bonus in 500 battles may be a little tedious but it’s manageable, as well as performing 1000 excellent attacks by doing the Time Actions correctly. The last objective will require quite a bit of luck from your side but given it’s only 50 times you may probably complete it without worrying about it too much if you like to fight battles a lot.
Luigi can never be absent in a Mario game and he makes a return in Paper Mario: Sticker Star, even though he’s nothing more than a cameo. You’ll find him in 5 different places
What does seeing Luigi do? Not much, to be honest: you can paperize him to make him look at you and then press A to push him out of the scene. If you do it for all 5 locations he’ll be at the head of the parade during the ending.
Probably the most time consuming secret is completing the Sticker Museum: to gain access to it you must free the toad trapped beneath the fountain by paperizing it and then restoring it right afterwards in the Decalburg Plaze. Enter the building across the Sticker Shop and head down to the Sticker Museum with the toad.
To restore the museum you must collect all stickers in the game, both attack and things types. A quick way to check if you have a new sticker to place in the museum is see if the light is lit in the corresponding room. If everuthing’s dark you don’t have any sticker to place. The rewards for completing the museum are unlocking a Sound Test Room and an enemy viewing room for things and battle stickers respectively.