There are ten secret trophies you can unlock in Mortal Kombat (aka Mortal Kombat 9, the 2011 version) for the PS3.
Best…Alternate…Ever! (Bronze) – Unlock Mileena’s 3rd Alternate Costume
Brotherhood of Shadow (Bronze) – Discover and fight Hidden Kombatant 4 in Arcade Ladder
Cold Fusion (Bronze) – Unlock Hidden Fighter “Cyber Sub-Zero”
Complet-ality (Bronze) – Perform 1 of each type of “-ality”
Finish Him? (Bronze) – Perform any fighter’s hidden finishing move
Hide and Seek (Bronzes) – Discover and fight Hidden Kombatant 2 in Arcade Ladder
Pit Master (Bronze) – Discover and fight Hidden Kombatant 3 in Arcade Ladder
Quan-Tease (Bronze) – Unlock Hidden Fighter “Quan Chi”
Ultimate Humiliation (Silver) – Perform every fighter’s hidden finishing move
You Found Me! (Bronze) – Discover and fight Hidden Kombatant 1 in Arcade Ladder
Check out my other guide if you need help finding the Hidden Kombatants for these hidden trophies.