Goku falls on his knees and sticks his butt up after suffering a humiliating defeat at the hands of Baby
Gohan in his work suit in Super Saiyan form.
 
Dragon Ball GT
Search for the Black Star Dragon Balls
Gohan and Videl in GT.After Dragon Ball Z, Gohan now works for Bulma's company as a researcher and, like Trunks, he rarely trains. He now is more concerned about being a good husband and father. He is one of the first to learn about Goku's transformation back into a child thanks to a wish made to the Black Star Dragon Balls by Emperor Pilaf. They all soon learn that if the Black Star Dragon Ball aren't collected and brought back to Earth within a year's time, the planet will explode.
Gohan, along with the help of Bulma and Videl, works on the spaceship used for Goku, Trunks, and Goten (later replaced by his daughter Pan) to go hunt the Black Star Dragon Balls. Even though he had apparently stopped with his training, he was still far stronger than most of his allies, including Trunks and Goten; he was arguably the closest to Goku and Vegeta's league in strength.
Baby, the evil parasite
Gohan battles Baby Goten.Gohan is later seen again visiting his mother and brother at Capsule Corp. with Videl. They tell Chi-Chi that Goten got into a fight somewhere (with Baby) over at Satan City. Goten returns shortly after, now under the control of Baby. Baby immediately realizes that Gohan is stronger than Goten and could be a little more sufficient body to help him infect Vegeta. Gohan also realizes something is not right with his brother. They two get into a little fight and decide to settle at a remote location. Baby Goten immediately plays the offensive against Gohan, trying to force him to power up (making it easier for him to takeover Gohan's body). Gohan refuses to do so, realizing that if he uses enough energy, he could hurt Goten. Baby Goten then powers up to full strength, cornering Gohan. Having no other choice, Gohan powers up to a Super Saiyan 2. Baby uses this opportunity and easily takes over Gohan's body. Baby tests Gohan's powers by attacking Piccolo in the area. Baby Gohan attacks Vegeta.Now with Gohan under his control, Baby seeks out his true target: Vegeta. Baby Gohan locates Vegeta and fights an even battle with the Saiyan prince. The fight is soon interrupted by the arrival of Goten, who Baby left an egg implanted inside of, rendering him under his control. With the help of Goten, one of Baby Gohan's attacks pierces Vegeta's skin, which Baby takes the opportunity to liqueify himself and enter Vegeta's body, gaining control of a more powerful host. However, just like Goten, Gohan has an egg implanted inside of him by Baby, bringing him under control of the Tuffle parasite.
Later, when Goku, Pan, and Trunks return home from outer space after collecting the Black-Star Dragon Balls (which Dende later gave to Baby so he could wish for Planet Plant to be restored), Gohan and Goten appear at their house and transform into Super Saiyans to immediately fight Goku and Pan. Gohan even promises to kill Pan and and fires an energy blast at her. However, Goku blocks the attack and the explosion knocks him and Pan down to the ground, rendering Pan unconsious. This angers Goku and he fights at full power, allowing him to gain the upper hand against the controlled Gohan and Goten. However, before Goku fires his Kamehameha at Gohan and Goten, Hercule and Majin Buu show up and explain what has happened. Gohan, Goten, Pan, and Trunks help restore Super Saiyan 4 Goku's energy.After being purified by the Sacred Water by Kibito Kai, Gohan, along with Goten, Trunks, and Pan help restore Goku's Super Saiyan 4 powers. Eventually, Goku manages to defeat Great Ape Baby, forcing the Tuffle parasite to flee from Vegeta's body, returning him back to normal. Baby then tries to escape in a spaceship, but Goku fires a powerful 10x Kamehameha up at the spaceship, blasting it to the sun while Baby was inside and killing the Tuffle for good. Piccolo's final farewell to Gohan before he dies.Later, Gohan helps in evacuating the population of Earth to the New Planet Plant before Earth's explosion. However, when Goku teleports back to Earth to get a little boy who was left behind during the evacuation, Piccolo suddenly appears, saves the boy, and gives Goku enough energy to teleport back. However, he chooses to share the same fate as the Earth. Moments before his death, Piccolo has a telepathic farewell conversation with Gohan. He tells him that he chooses to remain behind as his death would cause the Black Star Dragon Balls to be eternally turned to stone. This way, no wishes from the Black Star Dragon Balls will be made, saving the Earth from a future disaster. Gohan pleads for Piccolo to come with them, but Piccolo declines and tells him how proud he is of Gohan for how he has matured and the amazing potential he had displayed over the years. With the conversation over, Piccolo says his final goodbye to Gohan, who screams Piccolo's name in devastating sadness as his mentor dies a dramatic death in Earth's explosion.
The Earth is restored back to normal and everybody is back on it. Gohan says to Goku that he still misses Piccolo, but his father comforts him and says that he misses Piccolo, too, cheering him up. With that, Goku and Gohan are happy that the Earth and its inhabitants are safe for now.
Super 17, the ultimate android
Gohan battles General Rilldo.Gohan, along with the rest of the gang, fight the villains that escaped from Hell. He mainly battles a revived General Rilldo, saving Pan and Hercule from him. He and General Rilldo have an evenly matched fight before Rilldo unexpectedly uses his metal ray to turn Gohan's right arm and left leg into metal. He is nearly killed, but was saved at the last minute by Majuub.
He then battles (along with the Goten, Trunks, Vegeta, and Majuub) against Super 17, even firing an incredible Kamehameha attack, which had no effect (Super 17 absorbed it). He is the first to be knocked out, but is saved, along with the others by Goku, who, with the help of Android 18, eventually kills Super 17 with a Dragon Fist followed by a Kamehameha.
Transformations
Ozaru
Gohan has the ability to transform when the moon is full if he has a tail. Most of the time in this form gohan loses his mind and destroys everything around him but their have been times where his father calmed him and directed him to his target.
Super Saiyan 1
Gohan first gained this transformation in the hyperbolic time chamber. In this form Gohan is considered to be far stronger than the rest of the Z Fighters.
Super Saiyan 2
Gohan first gained this transformation in the hyperbolic time chamber while battling his father. In this form Gohan was far more power ful than all of the Z Fighters, Cell and the Cell jr's.
Super Saiyan 3
Gohan first gained this transformation after his fight with Super Buu (Gotenks and Piccolo Absorb). In this form Gohan is powerful
enough to take on Goku, Vegeta and Gotenks.
Golden Ozaru
Gohan first gained this transformation after Dragon Ball GT. After struggling for a while with his primal side Gohan gained his mind back and evolve.
Super Saiyan 4
Gohan first gained this transformation after Dragon Ball GT. After his evolution Gohan quickly gained this form. Gohan only uses this form to train with Vegeta.
Super Saiyan 5
Gohan first gained this transformation when his father got back from the Dragon Realm. Gohan uses this transformation to battle beings no one on earth can stop.
Special Forms
Hidden Potential
Gohan uses this potential like a power booster. In Dragon Ball Z this hidden potential always save him and his friend in dark times.
Great Saiyaman
This is Gohan's super hero alter ego. In this form Gohan protects those of Satan City who can't protect themselves.
Mystic/Ultimate
Gohan Gained this form after his training with Old Kai. In this form gohan was far more powerful the any other Z Fighter at that time in the Kid Buu Saga.
Infected
Gohan wa completely infected by Baby a Tuffle experiment. Baby uses Gohan and the other Saiyans to dow his bidding.
Baby Gohan
In this form Gohan is far more stronger than ever. He can also go Super Saiyan 1, 2 and 3 while Baby is in his mind and body.
The Shadow Dragons
Gohan in the Shadow Dragon Saga.Gohan, along with the rest, learn that thanks to the several wishes made to the Dragon Balls over the years, haved caused enough negative energy to turn the balls evil, causing seven powerful Shadow Dragons to emerge from them. Syn Shenron attacks Gohan.Pan and Goku are successful in hunting down and killing most of the dragons, but are no match for the powerful Syn Shenron. Gohan, Trunks, and Goten come to the rescue and revive Goku's energy, while Majuub holds off Syn Shenron. Shenron is, however, relentless at killing Goku, and tries his best to stop the re-powering. He is even successful in landing Gohan a devastating blow. Syn's efforts are in vain, though, as the three are able to restore Goku's energy.
Goku, now at full power, is more than enough to beat Syn Shenron, but things go for the worse when Syn absorbs all seven Dragon Balls, and transforms into Omega Shenron. Not even Goku is able to comprehend his power. Gohan and Goten in the final battle against Omega Shenron.The situation changes when Vegeta arrives and absorbed Blutz Waves from Bulma's new machine, to help him achieve Super Saiyan 4. Gohan warns Bulma that if given to much, he might lose control and became too powerful and uncontrollable (like Baby). However, Vegeta is successfully able to achieve Super Saiyan 4. It's not enough to stop Omega Shenron though, and Goku and Vegeta realize there's only one option: Fusion.
Gohan, Trunks, and Goten hold off Omega Shenron long for the Fusion to be success, forming Gogeta. Gogeta is far more powerful than Omega Shenron, but because he failed to take the fight seriously, the fusion expires before he kills Omega Shenron. It now seems that all hope is lost, but Goku attempts to form an ultimate Spirit Bomb. The rest hold battle Omega Shenron, but all are defeated easily by him. They do however, hold out long enough for Goku's attack to be complete and kill Omega Shenron, once and for all. Gohan lives out the rest of his life in peace with his family until dying of old age like the rest of the Z Fighters.