There are about 60 different player skins that are seperated into different categories. They are called the following: Holidays, Helicopter, Drone, Gyrocopter, UFO, Space, Jet, Beast, Blades, Mythical, and Special.
Holiday Skins are only purchasable during holidays. The only Holiday Skins so far are the Christmas and the Valentines Day Skins.
Helicopter, Drone, Gyrocopter, UFO, Space, Jet, Beast, Blades, and Mythical are available for purchase any time of the year, but some the Skins require the user to follow them or post about them on a third party site. As of right now, Special has only one skin, which is the Tournament Skin. The Tournament skin is earned by winning a competition.
In each group, (excluding Special) there is a skin that can only be bought once all the other skins in the group have been bought.