#1 Historic!

With the WWE's first all-women's PPV--Evolution--set to transpire this October, a rivalry between the biggest female heel in WWE in Stephanie and one of the biggest attractions in sports-entertainment in Rousey; is a no-brainer.
The WWE needs high-profile feuds for its first-ever all women's pay-per-view, and it couldn't possibly get any bigger than Stephanie vs. Ronda...And mind you, this time around there may not be the element of a Mixed Tag Team Match, so to speak.
While the professional wrestling rumor mill was abuzz with speculation that Rousey could face Nikki Bella at Evolution, a singles match between Rousey and Stephanie McMahon would be welcomed with open arms by the WWE Universe. Logic dictates that Rousey potentially laying a beat-down on her real-life friend Nikki, may not make for the most believable feud on-screen.
Although Rousey annihilating Nikki would be a sensible ending to the match--should the duo do battle at WWE Evolution--the very idea of a rushed feud between the two friends, this close to the PPV doesn't make sense.
Nevertheless, on the other hand, Rousey--who attacked Stephanie McMahon, leaving her in a heap with a nasty arm-bar on RAW--could garner a bigger pop and perform in a more believable feud with arch rival Stephanie McMahon as her opponent for Evolution.
Love her or hate her. Stephanie McMahon is here to stay.