In Mortal Kombat (aka Mortal Kombat 9, 2011 version) for the PS3 and Xbox 360, you can fight Classic Reptile in arcade mode for the hidden Pit Master achievement/trophy.
Look for a shadowy figure to fly across the moon on The Pit 2 Night stage, then get a double flawless victory and perform a stage fatality, and Classic Reptile will come out after the match to fight you.
Check out my other guide if you’re looking for the other Hidden Kombatants for achievements or trophies.
