WWE SmackDown vs. RAW 2010

To unlock this achievement you need to work your way through the BRAND WARFARE path in the ROAD TO WRESTLEMANIA story. From beginning to end this should only take 1 - 3 hours. You can make things easier if you set the games difficulty to EASY.

If you are going for the Nothing More to Collect then you will need to do the following

Week 2 - The Hardys, DX, Morrison and The Miz Entrance's
You must win the battle royal as either Triple H or John Cena.

Week 4 - John Cena Alternate Attire (Street Clothes)
You must put Kane through a table in less than 2:30 as John Cena.

Week 6 - Triple H Alternate Attire (DX)
Win the match in under 3 minutes as Triple H.

Week 11 - Alternate Attire for Miz and Morrison (Street clothes) and Dirt Sheet area for backstage
Win the handicap match as either John Cena or triple H.

WrestleMania 25 - Champion of Champions Title Belt
Win the WrestleMania Match.

Just go through the story. For the collector achievement, there is no need to save different ones because you get to use both Cena and HHH.