The poses feel rather stiff and restrained. Even moreso if you compare it to official MLSS sprites.
I think if you did more with the head it would make K Rool's personality really show. Like, maybe have his big eye bulge out more when he takes damage, or have his mouth gape wide open in certain frames. And he should have a taunt frame where he faces the camera smiling after throwing his crown.
There's a lot of personality in what you have so far, so just keep on spriting!