Gohan Character Facts

Gohan is a shy and studious intellectual child. As a child, he lacks the Saiyan fighting spirit. He must utilize his incredible half-breed Saiyan potential and emotional reserves to protect those he loves, becoming one of the most powerful Z Fighters. As an adult, he achieves his dream career of becoming a great scholar. 
Gohan, being only half-Saiyan, is unusual in his values and personality. These unique values and personality separate him from pure Saiyans; as powerful as he is, he does not like fighting much. However, when he is forced to fight, he shows special interest in protecting his family and friends. Like his father, Goku, Gohan has a pure and gentle heart. Also like his father, he has the typical Saiyan appetite. Besides concerning himself with his family (and his studies), Gohan has a strong attachment with his mentor: his father's former archrival Piccolo. After the death of Goku, Piccolo chose to train Gohan as he sensed the boy's potential power, which would be harnessed to help defend the Earth from the attack of the Saiyans. At first, the relationship with Piccolo is a frightening one, but after just one year, Piccolo admits his change because of the friendship he develops with Gohan and even sacrifices himself to save the boy. Because of this, Piccolo can be considered as a surrogate father for Gohan. Krillin also has influence on Gohan, as almost an uncle/nephew relationship, mainly because Krillin is Goku's closest friend. Though he claims he does not share the love of fighting Goku has, Gohan does indeed love martial arts and adventure. It is also clearly obvious he greatly enjoys being a there to help his friends.
This transformation occurs when a person with Saiyan heritage (and with a tail) looks directly at a full moon, or something that simulates its effects, such as Vegeta's Power Ball. The result is the waves from the moon stimulating a gland in their tails, enabling a seemingly unavoidable transformation. This is a complete genetic transformation, so it greatly affects Gohan's mental state. Because Gohan never had any proper training, Gohan loses all form of mental control, becoming a primal beast. However during his fight against Vegeta, Goku's words were able to reach Gohan enough to regain some of his rational thought and focus on his real enemy. Gohan only transforms into this state three times throughout the series, twice while he was training with Piccolo, and one final time when fighting Vegeta.
Gohan became a Super Saiyan at eleven years of age (if including the time spent in the Hyperbolic Time Chamber; in the manga he was only about 9 at the time), during the intense training he endured with his father to help him ascend. Gohan is the fourth character in the series to appear as a Super Saiyan, and he was also the youngest until the appearance of his brother Goten, who accesses the state effortlessly at seven years old.
Gohan is one of the first people to display full mastery over the Super Saiyan. Gohan had learned to perfect the Super Saiyan form with his father, when his father suggested that they remain transformed for extended periods of time so that they could master Super Saiyan, including all the unwanted behavioral effects. This mastery of the Super Saiyan enables full control over the energy output and consumption, completely diminishing strain on the body. Gohan continues to use this form during the Buu Saga, particularly when training with Goten.
Gohan was the first and the youngest character in the Dragon Ball series to reach Super Saiyan 2, achieving it at the age of 11. Of course this occurred when his dormant power was fully awakened through his rage at Perfect Cell for hurting his friends and killing the peaceful Android 16 (though it was revealed in flashback by Goku that Gohan actually achieved the transformed state while training in the Hyperbolic Time Chamber, but was too exhausted to maintain the form). While in this form, Gohan's hair stands straight up with the exception of one lock that hangs down. One thing is quite noticeable when he in particular manifests this transformation: his nature is prone to complete change, giving him an almost sadistic sense of mind. This is completely opposite of his natural reluctance and innocence when he is not transformed. 
Gohan's ultimate power up when the full extent of his dormant power is released during the Fusion Saga. This power up was achieved by a special ceremony performed by Old Kai. Although technically this ability is not exclusive to Gohan alone as the ceremony can be used to unlock anyone's sleeping powers, his was unusual in the amount of time it took to unlock due to his amazing potential unlike any other person who had undergone this ritual before. Gohan activates this ability in a similar fashion to the Super Saiyan transformation, however the colors of his aura, hair, and eyes do not change. Only subtle differences are present, including more pronounced facial features, more upright hair, and a large, uncolored aura.