Here is the full list of all 31 Final Fantasy XIII-2 achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Amassed a fortune in casino coins.
Defeated every worthy opponent.
Fully developed all abilities.
Witnessed every possible Paradox Ending.
Followed the story to its conclusion.
Obtained the highest possible result in the battle to determine the fate of the world.
Successfully used Feral Link abilities a significant number of times.
Completed an entire fragment category.
Completed every fragment category.
Performed a multitude of paradigm shifts.
Went the distance on chocobo-back.
Turned your back on empty dreams and joined the battle to save mankind.
Prepared to face a test of your determination in the rift where hidden truths slumber.
Defeated a powerful enemy with valiant skill.
Obtained five Cinematic Bonus rewards.
Spent a fortune at shops.
Acknowledged the threat facing the world, and decided to fight back.
Visited the place where the saviors of the past dream in crystal.
Performed a significant number of preemptive strikes.
Visited the place where clues to the future lie waiting to be discovered.
Defeated a powerful enemy with graceful poise.
Fought a significant number of battles without using the "Retry" option.
Defeated an army's worth of enemies.
Staggered a significant number of enemies.
Left behind a normal life, and began a journey through time.
Accepted a new fate in a world where everything has changed.
Responded swiftly to the appearance of enemies.
Defeated a powerful enemy with perfect execution.
Dealt 99,999 damage with a single attack.
Befriended a most unfriendly monster.
Defeated a powerful enemy on equal terms.