The colors on Brock's sprite look like they need some editing done. For starters, Brock has a fully saturated, 0 hue, MS Paint red as his main color. This doesn't suite the other graphics at all, and is just unpleasant to look at. If you made them yourself, then you should be fully capable of making Brock's graphics just as good. There's a few other instances of these colors on Brock's sprite and several other places, but it's important to change the main colors first.