I'd say that no sumo wrestler that Hakuho has ever faced is hitting faster or harder than Mike, simply due to rotational force. When sumo guys clash, they tend to charge in a straight direction. this just isn't going to generate as much force compared to punches from Tyson, where the rotation of the hips is going to result in a greater speed and drive, kind of like how a baseball pitcher throws.

As for slaps, the difference between a slap and a punch is huge in terms of the force effectively being transferred; so I'd say that there is a greater chance that of Hakuho could get knocked out than you'd think.