Per the 9/14/2015 Wrestling Observer Newsletter, Ronda Rousey will not be appearing at Wrestlemania 32, as she will be filming a movie during March and April.
"WWE: Well, so much for Ronda Rousey at WrestleMania this year. Rousey took a movie gig that will have her filming in Indonesia in March and April, so she said it’s not happening. She has said it before but was pretty direct about it this week"