Bidoof is completely unviable in every format except Little Cup. I'll provide an answer for Gen 7 LC: it's the most relevant tier that Bidoof is still decent in. Please note that it's outclassed by other Normal types like Bunnelby and Zigzagoon.
With Simple, Bidoof is able to abuse Swords Dance to get +4 Attack in 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. You're able to use Curse as well, but Swords Dance is generally better because it gives you more offensive power immediately.
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
Ability: Simple
EVs: 236 Atk / 116 Def / 116 SpD / 28 Spe
Adamant Nature
- Swords Dance
- Return
- Quick Attack
- Crunch
Please note that this can be checked by a lot of meta threats. 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, and physically bulky Pokemon with Eviolite (like Ferroseed), are able to stomach a few hits. It's an inconsistent strategy that should only be used when you don't really care about winning the match.
Hope I helped!
