Here is the full list of all 49 WWE '12 achievements worth 1,000 gamerscore. It takes around 25-30 hours to unlock all of the achievements on Xbox 360.
Win 37 times with Edge in one session (Single Player)
Content you uploaded to Community Creations is downloaded 5 or more times by other players
Execute a Finisher against all 44 areas in FREE BRAWL (Single Player)
Win a FREE BRAWL by throwing your opponent through the window (Single Player)
Pin or submit Undertaker in the WrestleMania arena on Legend difficulty (Single Player)
Win 5 championship titles in WWE UNIVERSE using a Custom Superstar (Single Player)
Win or defend one Tag Team Championship in WWE UNIVERSE using a Custom Superstar (Single Player)
Crawl to the ropes during a submission (Single Player)
Win 3 championship titles in WWE UNIVERSE using a Custom Superstar (Single Player)
Create a story that includes a Custom Superstar or Custom Arena
Use a movie created in Custom Entrance Video in an entrance scene (Single Player)
As WWE UNIVERSE Royal Rumble winner, participate in the Royal Rumble Winner's Event
Win a ONE ON THREE FREE BRAWL (Single Player)
Win 50 times on Hard difficulty or higher in one session (Single Player)
Become #1 Contender for a Championship in WWE UNIVERSE using a Custom Superstar (Single Player)
Win 20 times on Hard difficulty or higher in one session (Single Player)
Win at least once on Hard difficulty or higher (Single Player)
Build momentum up to 100% in WWE UNIVERSE using a Custom Superstar (Single Player)
Build momentum up to 75% in WWE UNIVERSE using a Custom Superstar (Single Player)
Break 50 tables, ladders, or chairs in one session (Single Player)
Break 20 tables, ladders, or chairs in one session (Single Player)
Win 20 times with submissions in one session (Single Player)
Cash in Money In The Bank in WWE UNIVERSE and win using a Custom Superstar (Single Player)
Upload one creation to the WWE Community Creations
Win the Money In The Bank match in WWE UNIVERSE using a Custom Superstar (Single Player)
Use COMEBACK ability to increase momentum to MAX (Single Player)
Complete HERO episode in ROAD TO WrestleMania (Single Player)
Win one Championship title in WWE UNIVERSE using a Custom Superstar (Single Player)
Win a Superstar match at the WWE UNIVERSE Draft Event (Single Player)
Win the final match at WWE UNIVERSE WrestleMania PPV (Single Player)
Complete OUTSIDER episode in ROAD TO WrestleMania (Single Player)
Use the limb targeting system to attack the same part 10 times in one match (Single Player)
Complete VILLAIN episode in ROAD TO WrestleMania (Single Player)
Create your own show in WWE Universe
Apply a Custom Logo to a Custom Superstar, Video, or Arena
Win using a Custom Superstar in WWE UNIVERSE (Single Player)
Interfere in an AI vs AI WWE UNIVERSE fight and beat all opponents (Single Player)
Create a front, top rope and corner finishing move in Custom Finisher Move
Create one arena in Create-An-Arena.
Hold an Exhibition at a Custom Arena (Single Player)
Interfere in an AI vs AI WWE UNIVERSE fight and beat one opponent (Single Player)
Perform a Wake-Up taunt, hit your finisher, and then win via pinfall (Single Player)
Reverse an opponent's finishing move (Single Player)
Injure an opponent in WWE UNIVERSE (Single Player)
Win a Royal Rumble match at Royal Rumble PPV in WWE UNIVERSE (Single Player)
Inflict heavy damage to opponent's head, arms, and legs (Single Player)
Win by applying a submission to a heavily damaged body part (Single Player)
Play in an Xbox LIVE match (Player match/Ranked match)
Review 5 or more items on Community Creations