Round I) Strongest/Most Advanced Terminator (regardless of canon) that Classic Mega Man can defeat (WITHOUT any Robot Master weapons)
Round II) Strongest Terminator model (regardless of canon) that can scrap Mega Man.
Bonus) Replace Classic Mega Man with X (no Maverick weapons, no armors, no upgrades).
Bonus II) Replace Classic Mega Man with Mega Man Trigger/Volnutt (no special weapons, no armor upgrades, etc.).