I can't find any calcs for either of them. With no values for either of their statistics, I'd assume that means we treat both of them as baseline.
Both of them have High Stamina with no justification and I would say that Superman is outranged... but his Range is listed as simply "Unknown".
Yeah. Guy with a practically human body with no powers. His range in combat is totally unknown. Can't be Standard Melee Range, right?
Brandon also beats Powerless Human in Lifting Strength, with Class 5 to Powerless Clark's Peak Human.
The only edges he has are his skill with Martial Arts and MAYBE his Intelligence where it's:
Brandon
Intelligence: At least Gifted (He is incredibly knowledgeable about multiple subjects, being above anyone in his school, even though he is just a kid)
Versus Superman's:
Intelligence: Extraordinary Genius (Is an excellent reporter, and is a master combatant, who is capable of defeating soldiers, martial artists, and aliens without powers, he is capable of using advanced Kryptonian tech, and is able to learn new languages in incredibly short periods of time. His intelligence is on par with Lex Luthor and other geniuses, learned how to use the Monitors' technology with a quick glance, and has outsmarted and outmanuvered masters of war and strategy.)
But I have no idea if that extensive-rating applies to powerless Superman, and I'm not sure he can use it.
He'd probably lose due to being outhaxed. Beyond exploiting the environment (SBA puts default location as Central Park, New York.) like say, snapping a telephone pole, breaking the power lines open, and using them to get Brandon electrocuted somehow, I can't see Clark winning.
And even then, telekinesis, &/or heat vision plus avoiding close combat via stealth or flight are probably easy wins so long as Heat Vision isn't more draining on Brandon's stamina.
What's Clark gonna do against heat vision? Block it with a rock? Hide in the water? Could Brandon's HV melt rocks or boil water, given he's only 9-B?
Unless Brandon stupidly stays in close combat, I can't see Superman winning this. Maybe a stomp, since one side is outhaxed, beat in most stats except speed, and has almost no feasible win conditions?