Custom Skins
To be completely honest I think custom skins should actually play a role in the actual game. There are lots of people will cool looking custom skins but if the other players dont have that custom then only the person with said skin can see it. Like make a drawing for who's awesome custom skin can actually make it in the game and make it only 5$ worth of RP or even make it available with IP 8,000+ IP but below 40,000 IP