Here is the full list of all 42 WWE 2K15 achievements.
2K Showcase - Complete "Best Friends, Bitter Enemies", 8/25/02 SummerSlam on Hard or higher.
2K Showcase - Complete "Hustle, Loyalty, Disrespect", 7/17/11 Money In The Bank on Hard or higher.
2K Showcase - Complete "Hustle, Loyalty, Disrespect", 11/20/11 Survivor Series on Hard or higher.
Beat Big Show using Rey Mysterio on Hard difficulty. (Single play)
2K Showcase - Beat "Best Friends, Bitter Enemies" on Legend difficulty.
2K Showcase - Beat "Hustle, Loyalty, Disrespect" on Legend difficulty.
Win with 50 different Superstars. (Single play)
Successfully perform a hot tag during a tag match. (Single play)
Perform The Shield's triple powerbomb. (Single play/Exhibition)
WWE Universe - Defeat Undertaker at WrestleMania using a custom Superstar.
Win in 20 match variations. (Single play)
WWE Universe - Win WrestleMania main event as the Royal Rumble winner. (Single play)
WWE Universe - Play and win WWE World Heavyweight Championship 3 times. (Single play)
WWE Universe - Play and win 50 matches.
MyCAREER - Participate in WrestleMania, Royal Rumble, SummerSlam, and Survivor Series.
MyCAREER - Win the WWE Championship.
Win a match using a Desperation Pin. (Single play)
Perform a giant swing with an OMG! Moment. (Single play/Exhibition)
MyCAREER - Earn an overall total of 1,000,000 VC.
Defeat John Cena using one of the NXT Superstars.
MyCAREER - Reach SmackDown.
2K Showcase - Complete all objectives.
2K Showcase - Complete "Best Friends, Bitter Enemies".
2K Showcase - Complete "Hustle, Loyalty, Disrespect".
2K Showcase - Complete 50% of all objectives.
Win a match by a leverage pin. (Single play)
Make an opponent tap out with a submission that is not a Finisher or Signature move. (Single Play)
MyCAREER - Have 5 attributes reach a value of 80 or higher.
Hit an opponent with a foreign object or put them through a table. (Single play)
Put your opponent through the announce table via any means. (Single play/Exhibition)
MyCAREER - Complete the NXT part.
Win 10 times using a custom Superstar.
MyCAREER - Complete the tutorial.
Win a match without reaching Stamina Level 3. (Single play)
Earn all achievements.
WWE Universe - Play and win 180 rivalry matches.
Strike or wrench an opponent in 5 different chain hold positions in 1 match. (Single play)
Eliminate 12 opponents with the same Superstar in a single Royal Rumble match. (Single play)
Earn 1000 points or more playing in a single ranked match.
Win 50 ranked matches.
Reach mid-carder rank playing ranked matches.
Upload some kind of user created content once.