Well, Harry's magic can give him an edge in many ways. For instance, he could use a simple levitation charm to make Dudley's feet leave the ground, which would be quite disorienting for Dudley and put Harry in a position of power.
Furthermore, Harry could use magic to create distractions. For example, he could make a sudden noise or create an illusion to startle Dudley. This would disrupt Dudley's concentration and give Harry an opportunity to either attack or escape the fight if he doesn't want to continue the physical confrontation.
Well, perhaps Dudley uses his street - smart knowledge. He might teach Harry some rough - and - tumble moves he's learned from his own scuffles in the neighborhood. For example, showing Harry how to dodge a punch quickly.
It could be that Dudley has his own reasons to oppose the dark forces that are after Harry. He might see that if Harry fails, it could also mean trouble for him and his family. So, he decides to train Harry to fight as a way of self - preservation as well as helping Harry. Another reason could be that Dudley has grown to respect Harry over time and wants to contribute to Harry's ability to defend himself against the many threats he faces.
In many Harry Potter fanfictions, a fight between Harry and Dudley can be quite intense. In the context of cartoons, it could be depicted in a more exaggerated way. Maybe Harry uses his magic in a comical way that still manages to overpower Dudley's brute force. For example, he could make Dudley's pants fall down every time he tries to punch, turning the fight into a humorous spectacle.
In cartoon fanfiction, the fight might start with Dudley making fun of Harry's wizarding world. Harry then retaliates by using a spell to make Dudley's hair grow really long and wild. Dudley tries to punch Harry but misses as Harry easily dodges with his quick reflexes learned from Quidditch. As the fight progresses, Harry might use more spells to turn Dudley's clothes into different colors or make his shoes too big to walk in.
In some fanfictions, Harry is shown to be an excellent fighter, having trained hard and developed strategies. But in others, his fighting abilities might not be the main focus or might be less developed.
Perhaps when Dudley throws the first punch and Harry, instead of retaliating physically at first, uses his wits and some quick - thinking magic to dodge and make Dudley look foolish. This could be a really intense moment as Dudley realizes Harry is not the easy target he used to be.
In some fanfictions, Harry Potter might learn to fight through intense training with experienced wizards or by discovering hidden magical combat techniques.
His basic spells like Stupefy could be used to stun the zombies. It would give him time to figure out a more permanent solution.
Often, Harry's knowledge of fighting in fanfiction comes from intense self-study and practice, as he realizes the importance of being well-prepared for the challenges ahead.
Well, it could be that the fight was so one - sided and unfair in the fanfiction that Harry just couldn't hold back his emotions. He might feel powerless or wronged.