As of today there are a few matches which are confirmed for Wrestlemania 29 and some matches which, based on what has happened on Raw the past few weeks, are rumoured to happen.
They are as follows:
John Cena vs Dwayne "The Rock" Johnson for the WWE Championship
Triple H vs Brock Lesnar
CM Punk vs The Undertaker
Jack Swagger vs Alberto Del Rio for the World Heavyweight Championship
Mark Henry vs Ryback based on their stare down after Ryback finished his match with Antonio Cesaro and Henry was making his way to the ring for his match against Zack Ryder
Randy Orton, Sheamus and The Big Show vs The Shield based on what happened after Raw went off the air. The Shield came down and attacked The Big Show. Prior to this weeks Raw, Sheamus and Orton out smarted The Shield. Hence a 3 on 3 tag-team match.