Here is the full list of all 37 FINAL FANTASY VI achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Earned all achievements.
Completed 100% of the Bestiary entries.
Got "Joker's Death" with the "Slot" command.
Reached level 50 for all party members.
Acquired all "Blitz" commands.
Won 10 battles in the coliseum.
Used the "Leap" command to learn 50 enemy techniques.
Obtained 500,000 gil.
Learned 20 enemy techniques.
Collected treasure from 100% of the chests.
Obtained all magicite.
Traveled to all the map locations.
Obtained all "Tools" commands.
Acquired all "Bushido" commands.
Completed 50% of the Bestiary entries.
Obtained all hidden items.
Reunited with 10 allies.
Obtained 15 pieces of magicite.
Collected treasure from 50% of the chests.
Defeated 1,000 monsters.
Defeated 2,000 monsters.
Defeated Kefka and restored peace to the world.
Reunited with 5 allies.
Reunited with 1 ally.
Witnessed the Warring Triad revive and destroy the world.
Obtained 100,000 gil.
Attended Emperor Gestahl's banquet and brokered peace.
Won an item at auction.
Completed 10% of the Bestiary entries.
Performed in the opera and obtained the airship.
Encountered Ramuh and obtained his magicite.
Collected treasure from 10% of the chests.
Protected the frozen esper and ousted the Imperial troops.
Obtained 10,000 gil.
Defeated 100 monsters.
Met with Banon and decided to oppose the Empire.
Encountered the frozen esper and awakened elsewhere.