>>78236847beating goku is a two folded question:
The first is - when - do you beat goku.
Goku is not invincible, in fact, he jobs quite a lot.
Around super saiyan goku could beat people that could destroy planets.
Now of course, this is the same for sailor moon. Early transformations were weak as fuck, Milenium queen Serenity might as well be Jesus.
So, which goku against which sailor moon?
Then, the second problem: how many times will they fight.
Goku, as being said, jobs a lot, but the thing is, he never loses twice. Goku true super power is that his strength keeps growing. This is why Goku vs Superman is also a rigged matchup: the first time Superman wins, the second time they fight together against a third menace, and by the next arc superman is so weak comparatively he is just a nanny for his children.
Usagi power rises, but not at the same scale, and not to infinite - the reason being, as stablished in canon, any time a Saiyan is close to dying, his power increases. Defeats only make Goku stronger.
So to say who wins, the real question is, how many rounds?
