The Speed Powerhouse's martial arts wasn't unique or anything special, very similar to the Bombardment Style that Adam had fought against while facing a Grandmaster Cultivator, but nowhere near and difficult to handle.
He was enraged after being used by Adam as a human shield and also wanted to test his speed against that of Adam, who appeared to also focus on speed, so instantly began attacking him, without waiting for his comrades to fight him together.
The rapid punches and kicks that he would unleash in quick succession were far from being as powerful as Marco's, but had similar speed and the way he fought would rely on his speed to overwhelm his opponent.
While although he may not have the power to match, after being hit by hundreds of rapid punches, no matter how weak they were, most would begin to suffer damage and breakdown.