Cosmetics are some of the many unlocks you'll obtain while playing BOMBFEST.
Every match will give you either: A costume, a hat, a stage, a bomb or a modifier.
For this achievement we will be focusing on the costumes and hats. Stages, bombs and modifiers are linked to the Full Toybox achievement.
Every match played will unlock one of the 5 types of unlockables.
So going into Settings and setting the matches to single rounds is ideal.
Most of these will be unlocked via natural progress as you work on unlocking the other achievements.
So just keep working on the other bomb/stage related achievements and you might unlock this and Full Toybox naturally. Here is a list of all the cosmetics you will need
COSTUMES
Jester
Strongman
Sailor
Knight
Pirate
Hunter
Boss
Pal
Diver
Apiarist
Traveler
Geisha
Jeanist
Prodigy
Baker
Courier
Minstrel
Tailor
Wizard
Apothecary
Blacksmith
Cat Person
Hats
Classic (Basic)
Posh
Mysterious
Optimisitic
Trendy
Heroic
Viking
Arcane
Feline
Incognito
Bomber
Wise
Carefree
Happy Little
Dusty
Adventuresome
Hip
Bumbling
Powered-Up
Iconic
High-Flying
Multi-Dimensional
Relaxed
Well-Versed
Disciplined
Star
Seafaring
Mega
Eccentric