While Goku is Dragon Ball’s main character, it’s arguable that his son Gohan has the most character development in all of Dragon Ball Z, and that’s something Dragon Ball Sparking Zero examines more closely in his branching paths.
There are fewer overall levels in Gohan’s campaign in the Episode Battle mode compared to some other characters in Dragon Ball Sparking Zero. The good news is that unlocking Gohan’s side missions only requires you to excel in combat, rather than the convoluted method of getting one of Vegeta’s branching paths or the choices you need to make in Goku’s side stories.