Here's a thread with a bunch of experiments with toonshading https://forums.unrealengine.com/showthread.php?306-trying-to-make-Toon-Shader-Material-on-UE4/page3
also, i dont think it looks as simple as slapping a toon shader .. it works together as a package, the stylistic proportions, the shaders, the lighting, the textures.. ..
CURRENT HEAD: This is what i have so far. But i feel its not toon enough yet, any suggestions as to how to toon it up? Maybe if i take a few days then come back to it, i can make the correct adjustments. C&C always welcome hmmm...something's not right just yet. maybe it'll all piece together once i finish the head eh?