I honestly don't see any reason to use Mandibuzz anymore. She's easily 2HKOed by three of the four special attackers in the S tier after SR (which she has a weakness to), which are on a majority of every team. Not to mention she's total Toxic and Taunt bait and defensive teams are just not as good as offensive teams. I've never been able to get her to work on a balanced team either.
The only thing I'd consider that she has going for her is her OK type synergy with Nidoqueen. But then the issue arises again, what is she really switching in on? Sceptile and Lilligant, if even? She has to Roost if she switches in on HP Rock (that or suicide take down Sceptile at the same time with BB), which is just a free switch for Esca (CB Megahorn is a OHKO after SR or BB recoil), Rhydon, Kabutops, etc.
I only see her as a deadweight and would argue she belongs at the very least in the D tier.