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