Firstly, your work is absolutely stunning. Seriously, your posts never fail to make my jaw drop!
On the subject of K. Rool's run cycle, it looks pretty spot-on! There are only a couple of suggestions I have.
His mouth seems to open and close a little quicker in the original- it looks like it's about in time with his arms, just one frame shorter. Perhaps a look at the sprite sheet would help?
It also seems to look a little straighter when it's open, though I'm not sure how much improvement could be done there.
Also, his left arm (K. Rool's perspective) seems to move a bit farther out in the original; I'm not sure if it's just the camera angle, though.
These are very minor points, the animation and model overall looks nearly perfect! It really boggles my mind.
I wish I could articulate better, but it's four in the morning here and my mind is moving rather slow. I'm sorry if this isn't really helpful.
Keep up the amazing work, I look forward to seeing more!