The group get their wishes and head back to Earth. 4 years later, everyone except Gohan is killed by #17 and #18. With Trunks not being around, Gohan has to act far more cautious when being the last hope for humanity and doesn't get himself killed, travelling back to the past. Knowing Goku won't be able to reach his full potential in Ginyu's body, he goes about training his past self to be the main hope for the Z-Warriors, staying in the past for about a year to train with past Gohan, Goku and Piccolo. In doing so, he'd teach that Gohan how to become a Super Saiyan.
2 years later, #19 and #20 arrive. Being the strongest of the group, Gohan takes on #19 and destroys him. Gero flees as in canon and activates #17 and #18. They defeat the Z-Warriors and kill Goku. Even if Gohan gets a large rage boost, it wouldn't be enough to take down the combined power of #16, #17 and #18. The Artificial Humans don't want to kill anyone else, however, so they let the group live and leave. Piccolo goes to fuse with Kami as in canon, though would be significantly weaker without fusing with Nail, let's say about as strong as his canon pre-Kami self. When Cell shows up, Piccolo and both Gohans have to confront him as a team, with Cell escaping with the Taiyoken.
Out of options, Piccolo would then remember the Rosat and see it as the only option. Both Gohans would go in there whilst Piccolo continues to observe things below. With no battle occurring, Cell is unable to find #17 and #18, yet is allowed to continue absorbing people without resistance. We'll say that with Future Gohan's mindset being a lot more experienced and akin to his father's, he goes about mastering Super Saiyan as Goku did. Once the two emerge, they'd raise their Ki in base to lure Cell out before transforming and quickly killing him. After some time, it's deemed that the present #17 and #18 can be left alone due to neither being a threat in power or personality anymore, with Future Gohan going back to his own timeline. Afterwards, Piccolo contacts Kaio to see if he can search out New Namek, with a group heading there and back to revive Goku.
With Goku still around and Gohan somewhat inspired by his future self, he doesn't slack off in his training. He kills Dabura 7 years later and Boo isn't revived. When Beerus shows up, the lack of Goten, Trunks, Vegeta or a Saiyan Goku would mean no Super Saiyan God, so Beerus leaves Earth disappointed after enjoying the food at the party. When Freeza is revived, Majin Boo not being killed and him being killed without using his full power would mean he'd have no reason to train when assaulting Earth, so he gets easily killed along with the Freeza Force. The Universe 6 and 7 tournament happens in which any of Universe 6's fighters solos due to how severely weaker the cast are without SSG happening. Zamasu Arc doesn't happen at all, nor does the Tournament of Power or the Broly Arc. Moro goes unstopped when he escapes and succeeds in whatever his end goal is.
