Here is the full list of all 19 WWE Legends of WrestleMania achievements worth 1,000 gamerscore.
Max out a Created Legend's attributes
Obtain all of the medals in Legend Killer Mode
Defeat the Favorite Legends Tier in Legend Killer Mode
Obtain all of the medals in WrestleMania Tour Mode
Clear all "Relive" matches in WrestleMania Tour Mode
Complete any match without pausing in the "Relive" section of WrestleMania Tour Mode
Obtain a medal in WrestleMania Tour Mode
Win a 30-Man Royal Rumble
Win a match using a manager in an Exhibition match
Win by using five or more reversals in a single match
Successfully perform a dive attack from all four corners
Win a match using a Tag Chain Struggle
Win a match using only grapple attacks
Become a Legend Killer in Legend Killer Mode in 30 minutes or less
Defeat 10 opponents with a Created Legend in a single tier in Legend Killer Mode
Obtain a medal in Legend Killer Mode
Win a match using a Chain Struggle
Have your Created Legend reach the Top rank in Hall of Fame Mode
Make a Created Legend