Are custom skins still "Illegal"?

Wondering because im thinking about making one for tryndamere https://vignette.wikia.nocookie.net/finalfantasy/images/d/d9/Kh-cloud.png/revision/latest?cb=20120407043102 Asking because i saw a couple threads stating it wasn't allowed anymore awhile ago ... Which im going to fail at terribly because i recall making said skins was pretty aids ;p