Oh man, I simply adore charcoal pieces! It reminds me so much of using color pastels, only, well, it's black and white! (I really like using both, but just for fun really, I'm not that great at either medium ><' )

I have to commend you on the pose here for him, also, it's great to see another male character get drawn as well! Don't think I've commented on a guy picture from you just yet, so it's a pleasure that your Machoke gets to be the one. ;3

What I would improve on in this, is, believe it or not, adding imperfections. Now I'm not talking about stray lines or blotches or anything. What I mean is he's perfectly symmetrical. As great a pose it is you've depicted, he's almost cardboard cutout, or rather...yes, those little paper dolls you cut out and repeat a dozen times in a chain? I could see him being that, hehe. x3

As far as the "imperfections" I'm talking about considering next time, they'd be like, the left arm is raised slightly higher than the right one. And the right leg is positioned a bit more forward towards the viewer than the left leg. These simple left and right differences make for a more natural feel, as almost everything living thing is asymmetrical in actuality! (Even people, you ever see a person's half of their face mirrored over to complete their head? Gah, they don't look anything like their real selves! >w< )

Anyway, those are my two cents, other than that, like I said, it a great pose you picked, looks really good, and it's most fitting for a Pokemon like Machoke. -w^