It's most likely just connection issues making the gif for Buzzwole unable to load properly. I think this is more common in formats like Random Battles, where there isn't a team preview, so each Pokemon gif is loaded separately and thus some appear to be fine while others can be corrupted. If you save it as a replay or have someone with a better connection view the battle, they'll most likely be able to see it properly.I got this glitch in a random battle where Buzzwole's entire sprite was missingView attachment 85381
Edit: Welcome to Smogon, BTW