If you like to think big, cartoonish skinning isn't exactly what you should be looking for. It's quite bottom of the barrel easy stuff. But I'd guess if anyone knew how to make skins like Kreshi and Skiwan, it'd more than likely be Kreshi and Skiwan.
But all smartass aside, there is no tutorial to learn to skin like someone. You can copy their style, but you won't find a tut on one persons specific style.
Every skinner has their own unique style. All you can do is find your own by trial and error.