Stickers are only modifiable parts in the game. You can put stickers anywhere on the body, partly on the body, and not on the body at all, but flies. Floating stickers were not shown.
Stickers are given every time you win a championship, including instant championships.
Stickers also account for the least an item can sell for, 200 from the beginning championship.
If you are low on coins and do not wish to have many stickers, it is wise to sell all but what you wish to keep
Stickers have their own rarity.