Hulk Jimmy was Jimmy's alter ego and monsterific form with freakishly-impossible strength and the ability to heal himself. He only appears in "The N-Men."
Jimmy gave into his Hulk form after feeling very angry inside of him due to still remembering the ridiculing comments that Cindy, Carl, Libby, and Sheen were saying to him all because he's orange and that he doesn't have a beneficial super-power before they were captured by the army.
Also, while attempting to conduct and develop a cure in his lab to remove the super-powers from their bodies, when Jimmy tried to do a submolecular scan, the screen in his lab read "FATAL GENE: 6:00:00" which means that Cindy, Carl, Libby and Sheen's powers are burning up their metabolisms, thus if a cure is not found in 6 hours they will die. Also, Jimmy attempting to motivate himself to working faster, ends up messing up his computer due to spilling a cans of Purple Flurp, on it. This leads to Jimmy enraged, and not even caring to find a cure when he remembers the years of mockery that his so-called "friends" did to him (especially Cindy), thus, his frustration and anger towards her leads to his transformation into Hulk Jimmy in frustration. It turns out Jimmy's powers weren't fully developed yet.
Founding out his true power, Hulk Jimmy goes renegade and starts a rampage in Retroville. During a "Save Our Mutants" rally because of the protesting of "no mutants in Retroville," Hulk Jimmy shows up by throwing a Pie Truck towards the crowd. He demands "blond girl" to smash her. When Jimmy's parents saw his true form, Judy was in absolute shock, while Hugh seemed too oblivious that this was one of Jimmy's side effects from the radiation, assuming that he's been working out. After ripping a Light Pole from its foundation, he attempts to attack the citizens, but is stopped by his parents. Even though his folks are willing to help him, the citizens throw tomatoes at him, which angers Jimmy more. Even with Judy's pleading towards the citizens to stop making him angry, they still further anger Jimmy nonetheless. Jimmy then attempts to attack the citizens, but is then stopped and attacked by Jet Fighters. Even though Jimmy takes down one, the other two jets retreat. Thus, Jimmy follows them to the desert, where his friends are kept, as he still has a revenge intent on them for making fun of him.
Jimmy's friends do break out of their confinement, in order to help Jimmy, having realized the error of their ways. Though, Jimmy reaches the desert, he is unable to attack the jets and lets them go. He later attempts to replenish his thirst from a nearby river, but instead, it is Jimmy's conscience in his reflection. His conscience warns him that if he doesn't get a hold of himself of his rage, he'll doom his friends. After being warned, a tank suddenly fires at Jimmy, and as Jimmy looks behind him and 3 tanks appeared, ordered by the general to attack him. One of the tanks fire at Jimmy, and Jimmy attacks the tank, using it as both a battering ram and a baseball bat to attack the other tanks. Though he throws the tank he was using, Cindy rescues the tank, and tells the general to call off his troops, and that they'll handle Hulk Jimmy. The General approves, and the N-Men go forward to encounter their "Hulked-Up" friend.
As the N-Men approach him, Cindy pleads to Jimmy to surrender. When Jimmy saw who she is and does not comply to her, and attacks her, and the N-Men. Carl suggests that Cindy should apologize, but the N-Men decide to attack Hulk Jimmy. Suddenly, Jimmy's conscience appears again, warning that if they continue to use their powers, they'll die. Though the N-Men do overpower Hulk Jimmy, their life forces start to take the toll on their lives. Hulk Jimmy is then shown to have survived Carl's atomic burp, and as he recovers, he grabs a big boulder, ready to kill Cindy, after years of insults and mockery. Before he can complete his revenge, Cindy gets down on her knees, begs Jimmy to not crush her and starts to apologize to him for hurting his feelings an always being mean to him. As Cindy tries to admit how wrong it was for her to treat Jimmy the way she did, Jimmy understandably assumes she's tricking him, but she pleas sincerity. Then, when Cindy tries to explain why she made fun him, she passes out due to her life force nearly gone. Jimmy holds Cindy and realizes that Cindy isn't a bad person after all. With his anger and rage towards Cindy gone, Jimmy reverts to his human form in time to finish the formula that would change them all back to normal, but Jimmy doesn't remember being turned into a scary monster.
He would have appeared in The League of Villains, had Carl not dropped Jimmy's N-Men packet.
He has orange skin, green hair and eyes, wears blue pants, and smells very fruity.
- This form of Jimmy is a mixture of the Hulk and the Thing of the Fantastic Four.
- He is the only N-Men not to appear in The League of Villains.
- He also could be a reference to Hulk's alternate color scheme from Marvel vs. Capcom 2.
- In the N-Men, he almost always says "JIMMY SMASH" and "JIMMY ANGRY" similar to Hulk.
- In one of the dialogues, Jimmy's mother, Judy said to Sam after hitting Jimmy "No! You're only making him angry!". This is a reference to the famous line in the original Incredible Hulk, "You're making me angry! You wouldn't like me when I'm angry!"
- Hulk Jimmy's color pattern (orange skin and blue pants) is very similar to the Hulk's color pattern (green skin and purple pants).
- Jimmy has only transformed into his Hulk form once.
- Like the Hulk, once angered, they both go renegade and destroy what is ever in their path.
- When Hulk Jimmy attacks the 3 tanks, it is an obvious scene to the 2003 film version of the Hulk entitled "Hulk," when the Incredible Hulk single-handedly destroys and overpowers 3 tanks in the desert.