Ahhhh, Butterfree. I always use it on my team as well. While it isn't a great competitive Pokemon by any stretch of the imagination, it does perform well against the pathetic AI. Here is your moveset.
Butterfree @ Quick Claw / Leftovers
Trait: Compoundeyes
EVs: 4 / HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Giga Drain
- Psychic
- Sleep Powder
- Stun Spore / Toxic
Typical Double Powder. Normally I suggest to NEVER use an item like Quick Claw, as 90% of the time it is like holding nothing at all, but in this instance you need to give Butterfree ever possible opportunity to go first. Standard process is Sleep Powder (or Stun Spore/Toxic for Early Birds), then either an appropriate attack or a switch to a different Pokemon for a free hit since the AI is too stupid to switch out. Personally, I typically switched to a SubPuncher to get a Sub up and then sweep through the "elite" 4.
Good luck.
