Random Starter Speculation time:
I was just looking up some stuff for Torracat, until I came across something called "Iron Shirt", and I was thinking about Litten3's leaked evo which depicts having a gray torso. Looking closer, its as if it was wearing a sleeveless shirt made of iron fur or something. If so, it just so happens that "Iron Shirt" is a chinese martial arts form, namely this:
Iron Shirt is a form of hard style martial art exercise for protecting the human body from impacts in a fight. This is one of the 72 arts of the Shaolin Temple. Some martial arts are based on the idea that a correctly trained body can withstand more damage than one that is untrained. Iron Shirt is said to be a series of exercises using many post stances, herbs, qigong and body movements to cause the body's natural energy (qi) to reinforce its structural strength. Practitioners believe that directing energy to parts of the body can reinforce these parts of the body to take blows against them. In the Shaolin version of Iron Shirt, the practitioner would do things such as lying on a stump or supporting tablets of granite on the chest with the goal of toughening the body.
What is more interesting, is that one of its variations is named Hǔ Xiào Jīn Zhōng Zhào, which translates to "Tiger Shouting Golden Bell Exercise
". Sound familiar no? Indeed, Torracat is a adolescent tiger cub who happens to depict a golden bell, otherwise its flame sac.
Maybe its just me, but I think this fits nicely with the Wrestler theme and if true, makes the evolution more sense wise. Perhaps....Litten3's Evo is a...Fire/Steel