For anyone asking if custom skins are bannable
No, they're not.
3 Comments
it depends on the program used to install them. If they modify any existing part of the game except the skin, they can and likely WILL get you banned.
what if the custom skin changes the color of someone's clone so you can very easily detect the real one?
As far as I know, allowed custom skins only affect your own champion, and no one else in game can see it. Having a skin that alters someone else's clone (especially an enemy) would qualify as an unfair advantage and could get you banned.