Kyuubi is more powerfull than all 7 tailled beasts together

[RikudouMadara]

Kurama could probably take on the first 5 tails 6 imo would be pushing it. If the eight tails is in then no imo.

 

[neilson]

I thought the jyubi was 10tails?

 

[DeadManWonderLand]

the bijuu's strength also depends upon the strength of its jinchuriki

When Naruto fought the bijuu, they were controlled by Obito and sealed into the husks of their previous hosts

As for a comparison in raw power? No, the kyuubi is not more powerful

The only reason he managed to deflect the Bijuu TBB was because he aimed under it, which lifted it up into the air

^^^^^

And the beast themselves say that the number of tails do not in any way shape or form determine the raw power of each beast