Round One Obito has just Sharingan.
Round Two Obito has Sharingan and Rinnegan.
Setting Five Kage Summit
With just Sharingan, the Kage are quite likely to take him out with some difficulty with Obito's Space-Time jutsu allowing him to phase through attacks.
With Rinnegan and Sharingan, Obito pulls an easy win via using the Six Paths jutsu to sick the Jinchuriki on the Kage.