Dingbat reserved Crobat more than 6 hours ago, so I'm stealing it.
Check
Crobat @ Black Sludge
Ability: Infiltrator
EVs: 232 HP / 100 Atk / 176 Spe
Jolly Nature
- Brave Bird
- U-turn
- Taunt
- Roost
Can switch in on CC/Dynamic punch and brush off confuse in a 1vs1 situation. Very unlikely that Machamp can pull a victory on this condition alone, as D-punch is 9-ko w/out confuse.
Survives Knock off w/ stealth rocks and wins 1vs1: 252+ Atk Choice Band Machamp Knock Off (97.5 BP) vs. 232 HP / 0 Def Crobat: 209-247 (56.6 - 66.9%) -- guaranteed 2HKO after Stealth Rock and Black Sludge recovery
Bullet punch does nothing... 252+ Atk Choice Band Machamp Bullet Punch vs. 232 HP / 0 Def Crobat: 87-103 (23.5 - 27.9%) -- guaranteed 4HKO after Stealth Rock and Black Sludge recovery
Reason why check: can't deal with Ice punch/stone edge
- 252+ Atk Choice Band Machamp Ice Punch vs. 232 HP / 0 Def Crobat: 324-382 (87.8 - 103.5%) -- guaranteed OHKO after Stealth Rock
- 252+ Atk Choice Band Machamp Stone Edge vs. 232 HP / 0 Def Crobat: 432-510 (117 - 138.2%) -- guaranteed OHKO
Also important to note, unfortunately:
+1 (guts) 252+ Atk Choice Band Machamp Knock Off (97.5 BP) vs. 232 HP / 0 Def Crobat: 314-370 (85 - 100.2%) -- guaranteed OHKO after Stealth Rock
More or less, this is a reasonable check to Machamp, both standard and used in the current metagame.