Which villain do you think Luffy gave to most painful and powerful blow to? In other words, who do you think got a painful defeat.
In case you don't know, this is how they were defeated:
Kuro: Gum Gum Bell-ed in the head.
Don Kreig: Smashed into the "wing" of Baratie.
Arlong: Buried under tons of rubble and debris.
Wapol: Gum Gum Bazooka-ed into who-knows-where.
Crocodile: Gum Gum Storm-ed
Eneru: Punched and smashed against the golden bell.
Gasparde: Gum Gum Bazooka-ed in a huge cyclone.