There are 4 male Superstars still being considered for Rousey's partner, according to Sports Illustrated. Those 4 are, in order of WWE's preference, The Rock, RAW General Manager Kurt Angle, SmackDown General Manager Shane McMahon and Seth Rollins. It's very possible that top WWE officials have already decided on Rousey's partner and these 4 names should be taken as a rumor for now.
WWE has wanted Rock for the role as a way to continue the feud that began between the two sides at WrestleMania 31 but as always, Rock's movie career may prevent a return to the ring. Angle and McMahon both have had recent mini-feuds with The Authority and Rollins faced Triple H at WrestleMania 33 last year.