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