Yordles are a unique race, so why can't they be completely unique?
Female yordles Have blue, and leathery skin, This is based off their proffessions, Tristana being a commando, she'd need tougher skin to withstand just that much more, and Poppy is both a master smith and a shield and hammer wielding Tank.
Male yordles have fur, the fur can change similar in type to a chameleon, giving them the ability to stealth (Teemo) Or they can harness the latent energies needed to change the colorations for combat purposes (Kennen)
Drone class yordles, the third gender, Take no part in reproduction, and have no form of desire or appeal towards or from the other yordles, instead, they focus on Streamlining new technologies, and innovative designs. (Heimerdinger and Corki) This third gender is the key to the Yordle success, and ongoing prescence in Piltover, which even now rivals The success of Zuan, without all the environmental issues. The idea of intimacy is foreign to them, and they hardly dwell on it, removing that distraction from their work environment.
What do you think?