"Is there really a Pajama Girl?"-Alex, Harper Knows
Superheroes are protagonists who are often featured in comic books and use their abilities to help and protect the innocents and fight evil doers.
The Enchanted Costume
When there's a POPCon in New York and the Emergency Wizards along with the Russo wizarding clan are tasked with assuring that magic is not exposed, because Wizards love to go to PopCons where they can mix along with the "nerds".
Alex tries to get unnoticed by Harper and magically zaps a superhero costume into her body. When she's "captured" by Justin and Hugh, she teleports away, enchanting the costume in the process. This gave the costume typical superhero powers. Later Alex steals the costume and gives it to Harper, which says the costume catch phrase, activating the superhero powers. Fortunately, the Emergency Wizards conjure ropes, making it look like an illusion trick. 
Russo Siblings as Comic Book Villains
Later Alex brings Captain Sherwood out of comic books into the real world but, as he is merely a heroic astronaut, he possesses no magical abilities. When Alex and Justin attempt to bring him back the station Alex turns them into comic book villains but, unlike Harper's enchanted costume, they seemed to not have gained any extra powers.