I made a similar thread in Naruto Discussion if I'm not wrong and I also said many things that could have made Pein won. Think about it, if Minato didn't came in time, Naruto would have really go 9 tails and that would defeat Pein. Why do I say so? Pein's ultimate move Chibaku Tensei was defeated by the 8 tails alone, however Pein underestimated Naruto and created a small Chibaku Tensei, and he said that he just have to make a bigger one. From here, we are not sure whether the 8 tails can truly defeat Pein since Nagato has pretty much about to be finished. (coughing blood) and could not create a bigger one. However, think about it. The Deva Path alone was able to make Naruto go 8 tails and even 9 if Minato didn't came in time and stop him. What if Nagato is fine? (Able to walk properly) If he joins in with the other paths of pein, Naruto's 8 tails will not stand a chance, he will have to go 9 tails to defeat Nagato. However even so, I still say it would be Pein winning or the most, a draw.
But still, Naruto was already defeated before he could even enter the fox mode. If it wasn't for Hinata saving him, he would have been captured back and his kyuubi would be extracted and he would die. However, Kishi could not kill off Naruto because of many reasons so he had shinobi to help him out and rather than seeing who won the battle, they had a talk instead. Do you guys really think Naruto WITHOUT anyone, not even the toad warriors, could really defeat the 6 paths of pein ALONE? No way man.