While Dragon Ball Super.
Gohan is the oldest son of Goku, and during Dragon Ball Z’s ‘Cell Games Saga’, he really came into his own as a powerful asset to the Z Fighters’ team as it was during that storyline that Gohan reached Super Saiyan for the first time. Since then, Gohan has mostly turned his attention away from fighting, only doing so reluctantly anytime the fate of the world is at stake. The most recent example of Gohan ing the other Z Fighters in battle was during Dragon Ball Super’s Tournament of Power, during which Gohan revealed that he was officially done relying on the inherent power of his Saiyan heritage to unlock new forms of power and would instead only focus on building up the parts of him that were human.
In Super Dragon Ball Heroes: Dark Demon Realm Mission! Chapter 13 by Yoshitaka Nagayama, an alternate version of Gohan (known as Xeno Gohan) ed an interdimensional police force known as the Time Patrol. Their mission is to stop the Dark Empire from emerging from the Dark Demon Realm and poisoning the mortal realm with their evil energy. In this chapter, Xeno Gohan and Xeno Goku of the Time Patrol–along with other including Vegeta, Goten, and Trunks–traveled to the Dragon Ball GT universe in order to stop the Dark Empire from attacking that timeline. Unfortunately, the Time Patrol was unsuccessful in keeping the Dark Empire’s evil influence at bay, and one of their soldiers was able to infect Super Saiyan 4 Gogeta, turning him into a terrifyingly powerful monster known as Dark Gogeta. To battle this foe, Xeno Goku and Xeno Vegeta fused and became Xeno Gogeta before powering up to Super Saiyan 4 themselves. However, even that wasn’t enough to stop Dark Gogeta, so Xeno Gohan found a way to unlock Super Saiyan 4 himself and ed his father and Vegeta in their battle to stop this nearly unbeatable villain.
This chapter of Super Dragon Ball Heroes proves that Gohan has the power to reach Super Saiyan 4 after controlling his Great Ape form and harnessing its power. Gohan has never wielded that amount of energy, and in Dragon Ball Super he never will. Super Saiyan 4 is the rawest form of Saiyan power as it is derived from their most animalistic transformation. Since Gohan has renounced his Saiyan heritage in Dragon Ball Super, he will never have the power that was wielded by his Xeno counterpart, which is an utter waste as his Time Patrol variant proves that Gohan is capable of becoming just as powerful as his father if he would only just accept every aspect of himself.
Now in defense of Dragon Ball Super, the transformation of Super Saiyan 4 isn’t canon in the Dragon Ball universe as no one in the main continuity has ever unlocked it, so it is unclear whether or not Gohan would even be able to achieve Super Saiyan 4 in Dragon Ball Super since it is unclear whether or not that transformation is even possible. However, the fact that his Time Patrol counterpart was strong enough to harness the power associated with that form proves that Gohan is much stronger than he has yet to be depicted in the current continuity, which proves either way that Gohan is waiting his potential in Dragon Ball Super by not using every avenue of power available to him as a Saiyan warrior.
