I would consider trying out this moveset for Mandibuzz:
Considering that Mandibuzz is slow anyway, if something Taunts it, it won't able to use Taunt itself. In which case, I think Whirlwind is better in order to deal with stat stallers. With Mandibuzz's low speed, you might as well just phase. I still suggest you try out the moveset in battle a few times, since you might feel Taunt is more useful in the end as it prevents status moves.
Another viable Defog user would be Crobat:
Crobat @ Black Sludge
Ability: Inner Focus
EVs: 252 HP, 252 Speed, 4 Atk
Since Crobat is so fast, the only things that will get through its Taunt are Prankster users like Sableye or Klefki. Stat spammers tend to be slow anyway, with the exception of Scolipede and Ninjask. Sadly, this set is pretty much a utility set. Depending on the rest of your team, you could choose to run Brave Bird > Taunt, in which case Infiltrator and more Atk EVs would be advisable.