Shazam also known as William Batson and Captain Marvel is a powerful fighter from the DC universe. He is a powerful superhero who is as powerful as Superman. Shazam is a powerful individual who has the ability to use magic.
Young William Batson has the ability to transform into the powerful being like Superman. When he echoes the name Shazam (which is the name of a powerful wizard) he can turn into a powerful entity. He has the power to use magic. He has superhuman strength which is capable of destroying buildings with a swing of the fist. Like Superman, he has the ability to fly. He has the capability to emit and use electricity. He can summon powerful lightning by saying his name Shazam loudly. One lightning blast is capable of utterly incapacitating his target.
In his battle against Superman in the Justice League animated series, he turned back into a child because he was detained by Superman and struck by the same lightning bolt that he unleashed by yelling Shazam. As a child, William Batson lacks all the superhuman capabilities that he has as Shazam. He will not be able to turn back into his super-powered form if someone covers his mouth and prevents him from saying the word Shazam otherwise.