No it's true without the tail they are weaker. Vegeta or Raditz mention it when they fight Goku, about how all Saiyans have tails, and cutting it makes you weaker. Also kid Goku has nimbus, he can fly around, a badass pole that stretches to infinity, and kamahamha. Kid Goku owns every Naruto character ever.
Also SS4 Goku versus fully maxed out Naruto isnt a fair fight. Goku would rip him nasty. Goku is one of the most powerful characters in anime. he dies and he'll just come back to lif. Goku is way to powerful.
I don't think it is a fact as Vegeta actually gained power after he lost his tail due to a zenkai. And which Naruto are we talking about exactly? I'm gonna say he would be able to maybe defeat Sage Mode Naruto. If not Sage Mode then I would say most definitely base. We haven't seen what SSJ Naruto can do yet so he shouldn't be included. This is Kid Goku before Roshi right?
"The great thing about the internet is you can make up a quote and claim somebody famous said it." ---George Washington
Gohan trained goku? yea thats essentailly fighting a 4 year old with ridicuous power vs Naruto whose been trained for like what was it 2 or 3 years with one of the best ninja ever. that's not a fair fight.
Also the discussion about him using the Dead Demon seal to kill Goku ss4.. it didn't kill Oro, and if goku dies, he comes back to ife with the dragon balls. If you want to go fully trained goku vs fully trained Naruto Goku is omnipotent by the end of the series. he goes off to train with the dragon and basically becoming a God. So fuly trained goku whips Naruto. Even though I'd say SS1 or SS3 would beat Naruto fully trained.