Future Gohan is the future counterpart of the mainstream Gohan. He is the mentor of Future Trunks. When Future Trunks returned from the future and destroyed Cell and the androids he wished Gohan with his arm back aswell as all
the people killed by the androids. Goku was also offered life, but Goku rejected simply stating "The Earth is in your hands now." In a alternate future Gohan never died or lost his arm. He was fighting with the androids when Android 17 said that he wished he could have killed Goku. Gohan's rage went flying through the roof and transformed into a SSJ2. He then easily beat Cell and the androids. Him and Trunks than found Android 16 and reprogrammed him to be good.
Gohan is stronger than the mainstream Gohan because of constant training while Gohan gave up fighting for awhile for school and work.
This Gohan never achieved his mystic form.