Personally, in my opinion, if you leave Kurama at his usual size, He would stomp Ninetales. (whether it be figuratively or literally). He is HUGE, the most powerful of the bijuu, and has a LOT of chakra. He could biju-bomb if he wants, and he doesn't really to be super accurate, as long as Ninetales is in the blast zone. Which, by the way, is really large. Now I know that speed is equalized, but if it wasn't Ninetales would never stand a chance.
However, if you equalize thier speed and SIZE, then I don't know who would win. I'm going with Ninetales on that one.
Again, this is just my opinion. And even though I am huge fans of both Naruto and Pokemon, I admit I am a little outdated on both. So, if this comment counts, great! If not, oh well. Maybe I can learn somethin'.