Bidoof is completely unviable in every format except LC. Please also not that it's outclassed there, but I'll provide an answer for Gen 7 LC. It's the most relevant, being the most popular tier Bidoof is at all viable in. Bear in mind that Bidoof is outclassed by other Normal types such as Bunnelby and Zigzagoon.
With Simple, Bidoof is able to abuse Curse or Swords Dance, getting double the stat changes. Using Swords Dance will effectively give Bidoof +4 Attack within one turn, the easiest way of setting up a sweep with Bidoof. Use an Adamant Nature for maximum damage output, and a Focus Sash in order to set up at least one Swords Dance.
Get your +4 in Attack (or +6, if you're feeling daring) and start sweeping with Return as your main STAB. Use Quick Attack to pick off Sash/Sturdy Pokemon. Crunch is the best final move in order to hit Ghost and Steel types. Use this set:
Bidoof @ Focus Sash / Eviolite
EVs: 236 Atk / 116 Def / 116 SpD / 28 Spe
- Swords Dance
- Quick Attack
Please note that this can be checked by a lot of things. Fake Out Mienfoo can ruin it, and so can Pokemon packing Mach Punch or Vacuum Wave. Riolu's Prankster can force Bidoof out with a phasing move, Z-moves can invalidate its existence, physically bulky Pokemon with Eviolite (like Ferroseed), have a pretty decent time walling your sweep attempts. It's certainly a dangerous strategy, but you have to know when to use it, and at what times.
Hope I helped!