Hmm... I could see here high crit chance sets being second the most eficient way to deal with Nature Fear. Ignoring your debuf on Attack could be handy, and ignoring positive boost on defense from Contrary pokemon. is also something what we could deal with.
Another strategy what could work especialy against Physical Nature Fear - Belly Drum. Ability to maximise your attack, while oponent will propably sometimes just swap his pokemon for that debuff could be sometimes effective. Not that much against, full attack debuf spam, but if oponent have, let's say two "Intimidate" users, you will be able to OHKO one of them on switch. If not one of them - propably something will be KOed.
Also... IF Bisharp will be banned, there is also a lot of other Defiant/Competetive users what gain similar boost. Also earlier mentioned Contrary...