The truth is that I like all the comparisons between the series and the movies.
I think that the M8 is born in a hypothetical alternative history where Vegeta ASSJ destroys Cell Semi Perfect, which makes Piccolo enter the Rosat to warn Goku and Gohan, therefore, these last 2 train with less pressure.
A few days pass and M8 occurs. The power scale is: Goku MSSJ (50%) = Goku SSJ (M8) >>>>> Vegeta ASSJ (Post Rosat / M8) > Future Trunks ASSJ (Post Rosat / M8) > Piccolo (M8) > Gohan SSJ (M8) = Gohan MSSJ (Suppressed) > Cell Semi Perfect (FP).
The Z Warriors return to Earth after the fight against Broly and are surprised that Cell had not died, as a result of his regeneration and that he had absorbed Android #18.
The Z Fighters start to train very hard and on one of those days the Ova of "The plan to eradicate the Saiyans" occurs.
A few days pass, the CG happens in the same way as in the Manga.
7 years pass and M10 occurs. I would venture to say that Gohan hadn't completely neglected his training and was therefore just as powerful as he was in CG.
A few weeks pass and TB25 occurs. Like Gohan in this alternate history, he didn't completely neglect his training and he surely raged at Dabura and was able to kill him.
That would make it the end of Babidi and Majin Boo is not born. Goku returns to Otherworld, some time passes and M11 occurs.