First Hero by Lucas Flint

In the aftermath of the Storm, Alex Fry (Beams) and Rubberman suffer a huge loss in support from the citizens of Golden City. Their popularity nosedives when the Lions, a team of elite government-sponsored superheroes, arrive in the city and promptly defeat a Zero Knight. Their success threatens Beams and his boss' livelihood as the people start to prefer the Lions over them.

But a bigger problem rolls into Golden City in the form of Nightbolt, Beams' mentor from West Texas. Nightbolt is seeking the ghost of a long-dead supervillain, who has made Beams her target for her revenge against Nightbolt for what he did to her thirty years ago.

And when it turns out that the Zero Knights still have some tricks up their sleeves, Beams must stop them, because their next attack might be the deadliest of them all.