Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
ok man, SD Buzzwole. The Tyrant, do you have some sample teams with Buzzwole so I can kick some ass with it XD. In Ubers Slowbro analysis Usage Tips
* keep in non mega forme as long as possible to preserve regenerator
* only mega evolve when absolutely necessary to tank hits,
These points sort of imply that normal Slowbro is better lol. Like why even use the Slowbronite when you want to keep as long as possible in normal form, just use lefties then. It sounds like mega-evolving is situational.
I think they do Mega Slowbro because Shell Armor and Iron Defense literally walls out MegaMence without Toxic. I haven't done Ubers in a while though fam. Nag Fireburn.
The points in the analysis hints to keep in regular Slowbro though. Like if you don't mega immediately, you can't switch your regular Slowbro into a Double-Edge after rocks.