BALAN WONDERWORLD

There are a total of 80 costumes to be found in Balan Wonderworld. You can check where they can be found by accessing the wardrobe via checkpoint or starting a level. Each tab shows the costumes that can be found in that chapter. Keep in mind that there is one costume to be found in Act 3 of every chapter, and you must also unlock the Balan costume for this trophy. Once you collect a costume, make sure you see the little animation dance your character does in order for the costume to register properly. This means even after getting the Balan costume (Look under Tim of Legend  for more information on how to obtain it) you must enter a level and equip it from the wardrobe so that it registers after leaving the wardrobe. The counter on the bottom of the wardrobe also tells you how many total costumes out of 80 you have found.

Costumes are not too bad to find, especially if you have the Balan costume and the Key Mouse costume from chapter 11. Key Mouse will allow you to obtain costumes without the need of a key. It's not a huge help, but does cut out a bit of legwork toward getting a costume at times. If you are having trouble finding any particular costumes, Trophygamers on YouTube has a great video detailing the location of each one here: Balan Wonderworld: All Costume Locations.