Future Trunks (and his Timeline)

Future Trunks (未来のトランクス), referred to in the series simply as Trunks, is the Saiyan and Human hybrid son of Vegeta and Bulma from an alternate future. By the time the Present

Trunks was born, the timeline had been altered by Future Trunks' trips to the past. Future Trunks hails from an alternate timeline in which Android 17 and Android 18 murdered the Z Fighters and proceeded to create apocalyptic hell on Earth. Future Trunks is trained by Future Gohan as a teenager and becomes a gifted fighter, swordsman and a Super Saiyan; traits that aid him greatly in the battle against the Androids after traveling back in time in order to save his own future.

-from the dragon ball wiki.

After Future Trunks and the Z-Fighters defeated Cell, Dr. Gero's ultimate creation, Trunks returned to his future and realized it hadn't been changed: the Androids were still there and his friends were still dead. This means his future had become an alternative Universe were the Androids killed the Z-Fighters. That's why Trunks' Universe is actually the original Universe of Goku, only that in this Universe Goku died because of an incureable sickness. But after having become so much stronger in the Past Universe, Trunks easily defeated the Androids and Cell from his Timeline. After this Trunks sets off to Namek and asks them if he can collect the Namekian Dragon Balls, when he tells the Namekians that he is a friend of Goku, he is allowed to get his three Wishes granted which were: When he returned to Earth, he told Gohan and #16 everything. Then they started to restore the Earth from all damage that the Androids made. and after having finished their work two years later, they formed the Neo Z Fighters.
 * Reviving his mentor Gohan
 * Giving him back his arm, which got cut off in a fight with the Androids
 * Reviving Android 16, because he actually didn't have any evil goals. He died to protect Earth's nature that he liked so much, but when #17 and #18 found out, they killed him.

Neo Z Fighters
The Neo Z Fighters are the new protectors of the Earth, the leaders are Future Trunks, Future Gohan and Android #16, who is now simply called Sixteen.

One of the new members is an old face: Videl, the wife of the Gohan from the other Universe. who later also becomes the wife of this Universe's Gohan and they have the same daughter as in the Past Universe:

Pan, or Future Pan. Future Pan looks a lot like Gohan's mother Chi Chi. She is obsessed with training as she spent a weak in the Reversed Hyperbolic Chamber (which is the second Hyperbolic Chamber, but in the original Chamber, one year inside there is equal to one day outside. In the Reversed Chamber one day training inside is equal to one year outside, which would be a pretty weird invention but it makes the person training inside much more stronger than after a normal training session of one day.) Pan uses it when she is 11 years old and spends an entire weak inside! Because of this, she comes out with an incredible amount of power, but she also aged 7 years! However Pan doesn't care and didn't ask Shenron to make her younger because with an older body, she believes she has more strength, ironically, she doesn't have a very muscular body after her 7-day training.

Another Neo Z Fighter is Vegeku (named after Goku and Vegeta), the son of Pan and Trunks, (yep, they have a son) Vegiku is a lot like his mother: he has an obsession with training. Because he is a descendant of both Goku and Vegeta, he is the strongest Saiyan from the Future Universe. Vegeku holds an insane hatred against criminals. He can become a Super Saiyan N, his own version of a Super Saiyan 2, combined with the power of a Super Saiyan God. (Beerus also visited the Earth, but instead of Goku, Vegeku obtained the Godly power. And he also went training with Whis, which made him so strong.

In the Buu saga, Gohan was able to kill Babidi before he could revive Majin Buu, so that Saga got skipped. One year later, Trunks met a very strong being called Nekomajin Z or just Z, Z met Goku when he accidentally teleported himself to the Other World, there he got trained by him. That's why since when he returned to Earth, he wears clothes similar to Goku's. Trunks asked him if he would like to join his Neo Z Fighter Team and he inmediately accepted. Z can transform into a Super Nekomajin, he invented this form after he observed Goku becoming a Super Saiyan.