Four-armed and dark strongman

The fog over the ruined arena of the planet Khoros slowly cleared. Ben, transformed into Strongman, had just dealt with another gang of space attackers. Confident, he stretched out all four arms and stretched his neck.
Suddenly, a heavy step made the ground tremble.
A giant figure emerged from the thick darkness. It was also a tetramand, but it did not resemble Ben's form at all. Its skin was jet black, its four eyes glowed with a blood-red light, and a deep battle scar ran through its upper right eye.
Dialogue:
Strongman: Who else are you? A doppelganger from another parallel universe? Dark Strongman: I'm Grimzag. And I'm not here to talk, you boy with someone else's watch.
Strongman: Wow, how serious. And where did the scar come from? Did he fall off his bike or not share a toy?
Grimzag: This scar is a reminder that true power is forged in the blood, not gained by pressing a button on your wrist.
Strongman: Well, then let's see whose strength is real! ...Grimzag made a lightning dash. His four fists collided with Strongman's fists with such a roar that a shock wave erupted in the air. The blow was so powerful that Ben flew back several meters.
Strongman: Uh... You can hit. But I'm just warming up!
Grimzag: You play hero, and I fought for survival. Your watch gives you the body of a tetramand, but not the heart of a warrior!
The strongman clenched his fists, clapped all four palms above his head, creating a powerful acoustic wave, and rushed in response.

Mysterious strongman