-- Dave Bautista recently stated that he had been approached by WWE t team up with Ronda Rousey as her partner against Stephanie McMahon and Triple H. This is very likely true as the original role was earmarked for The Rock so Batista was obviously an option once the Rock never worked out.
-- As of last week, Rey Mysterio had not signed any deal with WWE to appear at WrestleMania and in fact, he had not even been offered anything by the company. Mysterio has publically stated that he won't be wrestling at WrestleMania, but ultimately, you can't trust public statements especially around a major PPV.
Source: Wrestling Observer Newsletter. Subscription information & prices available at f4wonline.com