SmackDown vs RAW 2009

quick and simple way to get this achievement is to play thru story mode as Batista (because his stats are higher) and make sure you choose to save after your tag team match right before wrestlemania
play the wrestlemania match twice (once with Batista and once with Mysterio)
to play the match the second time just go to road to wrestlemania on the menu screen and choose continue instead of starting a new

Head to the Road to Wrestlemania mode and select the Rey Mysterio and Batista storyline. You can play as either character or have a second person controlling the other character. You can also swap who you want to play as - you don't need to stick with one player the entire way through.

You basically have 13 weeks left til Wrestlemania and are scheduled to around 1 match per week up until then. You need to work your way up to the last week and once you have done that the achievement will unlock. It really doesn't take all that long to do at all (Skipping the FMV's will also speed up the process).

It would be a good idea to check the requirements of certain matches so as to unlock bonus content which will aide you in getting other achievements later on.

To get this achievement without having to play the whole 13 weeks through again, when you have won the championship at wrestlemania with one character. Load the last save up and select the other character and then win the same match at wrestlemania and the achievement will appear after the second time.