It's not hard work really, just open it in paint/photoshop, or whatever else you might use. It would probably be a bit easier to edit the sprite rather than the battler. If you don't think you can do it, I can give it a shot. I've only done very minimal stuff with spriting though.
Edit:
Here's my attempt at it. This is my first attempt at recoloring. Let me know what you think, I can also try to get rid of the red bandana if you'd like.
Edit2: I took out the bandana, and I fixed his shoes. For some reason on a couple of them he had one blue shoe. xD