Complete Single Player mode with an ability to unlock it's corresponding costume.

Costume	How to unlock
Rare Archer Hat	Complete Single Player with the Archer ability.
Rare Beam Hat	Complete Single Player with the Beam ability.
Rare Beetle Hat	Complete Single Player with the Beetle ability.
Rare Bell	Complete Single Player with the Bell ability.
Rare Bomb Hat	Complete Single Player with the Bomb ability.
Rare Cutter Helmet	Complete Single Player with the Cutter ability.
Rare Fighter Headband	Complete Single Player with the Fighter ability.
Rare Hammer	Complete Single Player with the Hammer ability.
Rare Ninja Headdress	Complete Single Player with the Ninja ability.
Rare Parasol	Complete Single Player with the Parasol ability.
Rare Sword Helmet	Complete Single Player with the Sword ability.
Rare Whip	Complete Single Player with the Whip ability.