For what FnF is worth, we saw Freeza can instantly go into his true form if he wishes, so he may just do that or go straight to his 3rd form so that he doesn't get instantly overpowered. That said, everyone dies by the time Goku gets there, Goku goes SSJ and the events of Namek transpire similarly apart from Goku being sure to kill Freeza once he has the chance and having more time to escape now that he doesn't have to stall for Gohan and likely saves Bulma in that time. He goes to Yardrat and learns Shunkan Ido, though it makes little difference in terms of extending the plot much due to the Dragon Balls being gone. Goku dies from the Heart Virus and the Artificial Humans face no resistance in the future timeline and assuming Future Bulma survived long enough to complete the Time Machine, there'd only be a chance of winning if Goku uses the Rosat as a last resort. Assuming he does, the cyborgs are easily killed as is Cell, with Goku being less likely to take things casually and allow Cell to blow up when he's the only warrior left. As for the Boo Arc, he may be able to defeat Dabura, though it wouldn't be easy when he'd have to face Yakon by himself beforehand and likely wouldn't unlock SS2. This is the best case scenario. Worst case, he forgets about the Rosat and is killed by #19 and #20.
Bringing Super into the mix, the best case scenario ends when Goku doesn't have enough Saiyans to become a God and Beerus destroys the Earth.
