i wonder what that would be like. i'm guessing naruto would use sage mode while the kyuubi is fighting then i can see that but i can't see kurama using sage mode because i don't think he trained under frog fu
That won't happen. It requires the user's body to be still to gather the Sage Chakra, and since Naruto and Kurama share a body, no matter who's in control, they'll be moving.