I exist, to assist!
Assista-Boy is cheerful and likes to help superheroes which is probably why he's a sidekick. However, if Assista-Boy gets upset or sad, he turns into a sad monster that's orange and destructive.
Before Barb and Hank retired, Assista-Boy used to help them with duties they were supposed to do whilst they were superheroes.
Assista-Boy returns to rejoins Barb and Hank in Side-Kicking and Screaming. He gives Barb and Hank tickets to go to the Metroburg Super Spa. When Max forges Barb and Hank's signature, it allows the Hero League to give authorize that Assita-Boy could be the Thunder Twins' sidekick. Assita-Boy gives out Hero Share calendars to Phoebe and Max so they equally could have the same amount of time. Assita-Boy did a weird way of choosing who could be Hero A. Since Phoebe has the authorization to use Assista-Boy as her sidekick, he went with Phoebe to workout.
Without Phoebe knowing, when she was at the workout, she took time of Max. As a result, he rips some pockets off Phoebe's cape to show his frustration. Phoebe decides to destroy the homework Assita-Boy did for Max. In Max's Lair, they were bickering and Assita-Boy warns them he would turn into a sad monster. Phoebe and Max didn't believe him and laughs about it. He isn't joking. Soon later, he turns into an orange, nasty monster.
Assista-Boy begins attacking the Thunder Twins. Phoebe uses her freeze breath against him but it does no damage. Max is left with Assita-Boy because Phoebe ran upstairs. Assita-Boy carries Max out of the house. When Dr. Colosso tries to help, Assista-Boy ends up throwing Dr. Colosso so far he lands in Metroburg Super Spa. Phoebe and Max does cartwheels so he would turn back to normal because Assista-Boy loves cartwheeling. However, it didn't work so Phoebe comes up with another plan that is to pretend that they get along together. Assista-Boy, as an orange monster, carries on throwing stuff at Phoebe and Max. The Thunder Twins used Phoebe's super suit, which is thundertanium material. Assista-Boy is glad that they are sharing. Assista-Boy returns back to his regular self. At the same moment, Barb and Hank returns and grounds Phoebe and Max for using Assista-Boy without their permission. Assista-Boy pretends that he is turning back to his sad monster which makes Phoebe and Max ran. He told Barb and Hank it was a prank and they laughed about tricking Phoebe and Max.
- Assista-Boy was mentioned in Who's Your Mommy.