Axew disguise themselves as leaves so they can drop onto your head. They're pretty much evil geniuses.

Axew, known as Headlouce in Canada, is a parasitic Pokemon that lives in your hair. Seriously. It's in there now. Check. Anyways, Axew is dangerous, man. Once infected with this Pokemon, the victim's hair color will inexplicably change to inhuman shades. Cataloged cases include blue, red, (purplely red if you're a computer) and long-term exposures result in your hair growing into the size of small hedge, and becoming the color of vomit purple (what, you haven't had purple vomit before?). If you're a weeaboo, you've probably seen many victims of Axew floating around in your crappy Japanese animations. Fortunately for us, Empoleon can safely consume these beasts on Saturday afternoons.

It evolves into a repaint of itself, which is so unimpressive that it has to evolve into A FREAKING GOLDEN DRAGON AXE THINGIE afterwards.