Maxum Man comes from a family of superheroes that all seem to wear similar costumes and have similar powers. As such, you can look to Maxum Mom to see his powers since she appears sometimes. Along with that, old videos used for the school show him fighting crime, so some of his powers are seen there as well. He and his family seem to have the typical Superman-like arrangement of powers, namely super strength, super speed, laser vision, etc. however it's unknown what/if his weaknesses are, assuming there are any.