Butch is a higher ranking Team Rocket than Jesse and James, and obviously way more trusted by Giovanni. His partner is Cassidy, and they are the rivals of Jesse and James. But, I have to point out, Cassidy is like Gary to Jesse, and Butch and James seem to just hate each other because their partners are demanding it from them or something.
What do we know about him? He has a Mankey or Primeape (I'm still too lazy to actually check it), and... well... yeah.
He is "eviler" than Jesse and James, more like the criminal he actually is. He and Cassidy's schemes are a lot smarter than most of Jesse and James's, and they seem to succeed a lot more with them too, even though they have been beaten by Ash in all episodes they appear in this far (most of this is in the Cassidy section as well). Butch also seems to be way more like a man than James (Cassidy probably treats him better than Jesse treats her partner anyway), and... don't you know all this crap anyway?
There isn't anything much to say about him, but if he and Cassidy were characters that meant anything to the show they would be deeper, but they aren't anything we would die without, and they aren't likely to get anything more either. I have noticed, however, that they act a lot like Jesse and James did in the very first episodes, so... okay, they are cartoons. But that doesn't mean that their character is shortened down to what they are in the show.
He has, together with Cassidy, appeared in three episodes and a fourth Japanese one, but that one is something like the Ss. Anne ones with four parts at all, and I'm not sure if they are in only one of them. Maybe I also should mention he has a Houndoom there. Or Hitmontop. But I think the Houndoom was his.