I think Froch's shot on Groves would've floored most Heavies, a flash Kd at the very least.
147 lb Marquez on the night he Ko'd Pacquiao (Only)is probably the smallest guy I've seen with near HW power. That early knockdown was super explosive and more shocking I thought than the punch Pacquiao fell into.
Back in the day prolly Bob Fitzsimmons...
most good punchers could, depending on the heavyweight obviously. roger mayweather once knocked a HW cold in sparring and he was fighting at 130 at the time.
hearns, mccellan, julian jackson, toney, barkley, ggg, norris, mugabi, benn etc could all KO heavyweights.
As above, Ali Raymi has KO'd men over 400lbs, all in the 1st minute of their unsanctioned war to the death
When criminals are given the death sentence, they send them to Ali Raymi.
Heavyweights are lucky that raymi demands cushioned rings. He is merciful in that the cushioning doesn't allow him to transfer all his power. Al raymi would definitely ko heavyweights but the media chooses not to hype him.
The Deity that is Ali Raymi is known to dispose of mortal Heavyweights with ease. 112 lbs of raw Godlike energy condensed into a lightning fast, sniper like fist drilling into a fleshy torso would fold anyone on this planet.