He’s the only person in the JL with a nerf for Superman. He could’ve blasted him in the face with magical energy and been ok whereas Superman would be a little fucked up. Dude has the only superpower that actually hurts his consistently and they just killed him off.
He’s just as strong, plus has magic that weakens Superman. The only reason why Shazam has never been able to take him is because he’s a child that doesn’t want to merc the hero he looks up to. But in this universe where they stop holding back he should’ve been able to take him, granted while still taking a serious beating in the process.
"Shazam" is the name of the wizard that granted Billy Batson his powers. Captain Marvel is what Billy transforms into when he says Shazam. This person is not named Shazam. That is Billy.