Future Goku came back a day to Earth?

[Captain Cadaver]

In this scenario, Goku uses his 1 day on Earth to help out Gohan and Trunks against #17 and #18 the day before Gohan would normally die. How does his presence here change this timeline (or more)?

 

[Papasmurf]

He'd have gotten around 14 years of training in, so regardless of whether he attains MSSJ or SSJ2/3, he should be strong enough to destroy the two cyborgs. (He might have a harder time with the ones in Cell's timeline though, if the theory about them being as strong as the ones in the main timeline is to be believed) Afterwards, Cell appears and likely just drains all of Earth before being confronted by Trunks and Gohan, who due to the ensuing peace haven't trained much and are picked apart. The main timeline thus isn't created and Cell, due to having no time machine, just destroys the planet in frustration before moving onto other worlds to absorb more lifeforms.

 

[Captain Cadaver]

Do you think Goku would just charge in to fix things though? Considering how he acted in the Boo Arc in preparing the next generation for greater threats, don't you think he'd inform Gohan and Trunks of the Rosat as well as teach them the fusion dance or focus primarily on getting them into the position to solve this problem?

 

[Papasmurf]

Trunks didn't seem to know of the RoSaT and it was stated that the Senzu plant died, so it wouldn't surprise me if the future cyborgs already destroyed the Karin-to and Kami's palace. The fusion dance wouldn't work since Trunks was still a young teenager at the time that Gohan would've otherwise died without Galu's intervention, making the size difference too big. I doubt Cell would give them time to fuse either if he ambushed them to try and find out where the cyborgs were, as well.

 

[Hector]

Depends on whether you think Present Goku having his body in the Otherworld was a result of his sacrifice against Cell or he would have kept his body anyway. In the first case, he just gets killed a second time. In the second case, he solos Androids and, since there is no time machine, no Zamasu Saga either.

 

[Captain Cadaver]

Depends on whether you think Present Goku having his body in the Otherworld was a result of his sacrifice against Cell or he would have kept his body anyway.

If he was allowed to keep it once, regardless of the circumstances, I don't see why he wouldn't be allowed to do so again; especially when he'd done more to save the mortal realm on a galactic scale since then.