Yeah, it kinda made sense that Biff and Cassidy gradually became more Jesse and James-like as they gained a bigger failure rate (especially since they originally acted a lot like they did in early Kanto before their own bubble was popped). I suspect by AG they were starting to lose favour with Giovanni and becoming more desperate.I guess that Butch and Cassidy were just one Giovanni's good side because of how much better they were than the trio although they were becoming more and more like their rivals with each evil plan that they failed at.
I do wonder how a future Botch and Cassidy appearance would work now the main trio have actually got into Giovanni better graces.