Final Fantasy VI > Chapter 12: Kefka's Tower
It goes without saying that you should complete all sidequests and collect all espers first, unless you're trying to complete some challenge without doing everything in the game. Two dragons will have to be fought inside Kefka's tower to get the Crusader Esper, so you may wish to go here earlier and leave again.
Choosing your party
You will be able to use at most 12 characters in the final battle with Kefka, and against all the dungeons and bosses preceding that point. All your groups will engage in their own boss fights and exploration so you will need three strong parties.
It should be noted that if one of your parties possess the Moogle Charm and equips it on Mog that party can explore Kekfa's Tower without worrying about anything but boss fights. This may be able to be used to protect a weak party early on in picking up equipment, but in general you will still need three strong parties to complete some areas where the path divides.
It should also be noted that due to 2 extra characters being placed in the game, Umaro and Gogo, you will have two characters which will not be able to be used in the final battle. In short, you should decide well in advance to fighting in Kefka's Tower which two characters you should choose to ignore and not level up at all. The following is some of my consideration for doing so:
(when I say a character is "required" for a particular task it means that it's unavoidable for using them in a particular scenario which normally involves boss fights and levelling up)
- Celes-Required for all the early quests up until you get the airship, has strong magical ability.
- Edgar-Required for early quests in the world of ruin as well, his strong complement of tools and the chainsaw make him invaluable.
- Sabin-Also required for early quests, his blitzes and the bum rush make him invaluable.
- Setzer-Required for the quest in Darril's tomb. Slots is unreliable, although GP toss can be valuable.
- Locke-Required for looting Narshe, and a good deal of the missions in the world of balance.
- Cyan-Strong physical attacks, and the swordtechs are very useful when you have the time to charge up.
- Terra-Very strong magical ability, she's practically the main character anyway, and she can morph into an Esper for more power.
- Mog-Required in order to complete the sidequest to recruit Umaro. His dance skills are useful but unpredictable sometimes.
- Strago-Required to complete the Hidon sidequest, strong magical ability and useful lores.
- Gogo-The most flexible character in the game, never needs to be trained in magic, and can copy any characters moves and techniques. Absolutely essential.
- Umaro-Strong physical attacks and a force to be reckoned with when he has the rage ring or blizzard orb.
- Shadow-Not required for any quests, but used for the floating island in the world of balance so he may already be levelled up enough to justify keeping him.
- Relm-Not required for any quests, strong magical ability, Sketch is a little dangerous to use because of the bug.
- Gau-Not required for any quests, rages can be useful early on but they can be a hassle to figure out.
In short, I recommend ditching Gau and Relm because you likely won't be using them anyway on any of your required quests and their abilities aren't as useful as some of the others. You could also make a case for leaving out Setzer or Shadow because of their special abilities, and that after a certain point the built in "abilities" of the character don't matter as much since you may chiefly rely on magical attacks.
Anyway, you will need to split your party up into three teams.
Your strongest physical attackers are: Edgar, Sabin, and Cyan. Edgar and Sabin both have physical attacks which can easily do 9999 damage and Cyan has powerful multi-enemy physical attacks when given time to charge up.
Your strongest magic users are: Terra, Celes, and Strago. Terra, Celes, and Strago have the highest magical ability out of the characters I chose to keep so it makes sense to split them up and teach them the most magic.
"Wildcard" characters are: Shadow, Locke, and Gogo. Shadow and Locke should normally receive the Genji Glove and one of them could get the atma weapon or offering to make them even more powerful to compensate for their lack of innate special abilities. Whatever team gets Gogo has access to the skills of any other character and all the magic known by other characters in that party, so it will be strong enough to compensate for other disadvantages.
Secondary attack characters are: Mog, Setzer, Umaro. They all have decent special abilities but are generally not as reliable. Whatever team gets Umaro will probably be strong enough to compensate for other disadvantages if you give him the rage ring or blizzard orb.
From the previous list you should give each party a strong physical attacker, magic user, wildcard character, and secondary attacker. Gogo and Umaro can be kept on separate teams and you can do your own job of balancing things out. In general each party should also have at least one person who knows Ultima or an extremely powerful magic spell, and each party should be able to cast strong healing and life spells.
Beating Kefka's Tower
If you're just in Kefka's tower to kill the two dragons you need to get the crusader esper, look at Part I for the second and third party, and assign your strongest members to those groups. Otherwise, split up your parties however you'd like, and hopefully you've got a good collection of spells, party members, and abilities at your disposal.
You can return to the airship by going back to your starting positions and pressing A to grab onto the floating hook when it nears your party.
First Party: Part I
Second Party: Part I
Don't forget to equip your party, and head to the bottom left to pass through a passage into another room. Go to the top left corner of that room for a Minerva armor. Head into the next room, and you can head up to pick up a tack star or down to find a few prison cells, the very left of which contains an optional boss fight with the Atma Weapon. Use your best physical attacks in general and ultima is always a safe bet.
After you beat it, it turns into a save point and you can head down to drop through a hole into a new area. Exit to the next area, and you'll see two pipes, one which drops you down a hole earlier on so you can head back, and one which leads you on to another area. Pick up the chest and head down. Cross over the right conveyer belt and go to the left corner to find another chest. You can cross back on the other conveyer belt, or go in the left entrance to pick up a ribbon and flip a switch which allows another party to advance. Head outside and into the right entrance to get ready for a fight with the Gold Dragon. The fight is strictly optional but recommended if you intend to get the Crusader Esper. The dragon is weak against water, use your best physical or unblockable magic attacks to take it down. When you're done, send your party through the door on the left and have them stand on the switch to get ready to open the door.
Third Party: Part I
Equip your party, and head down the left conveyer belt to go forward. Open the chest and go into the first door you find and follow the path to pick up two more chests. Go back outside and to the bottom of the path to reach another area, back inside the magitek factory. Follow the bottom wall very carefully in this area to find a hidden path which will give you another Aegis shield, one of the best shields in the game. You'll need to go down through the bottom wall, to the left when it branches, then down, to the right, and up. If you're using an emulator you can usually remove the background layers to see the hidden paths. After you get the chest and head back out, cross up the conveyer belt to reach a new area. You can return to the previous area by entering the pipe, or move to the left for a boss fight. The main boss entity will reflect your magic attacks and do some nice delta hits with its other components, physical attacks and unblockable spells are your best bets as always.
After you beat the boss, head down through the next area and clear it out of treasure chests. Make sure you use the chest in the lower left corner with the glowing red dot to open up a path for another party. Follow the conveyer belts around the area to pick up a rainbow crush as well. After that, head through the door to enter the hall where the Skull Dragon can be found. This one is weak against fire and pearl magic, so use those or the best spells and attacks at your disposal. If this is your final dragon you should also receive the Crusader Esper to teach you Meteor and Merton.
When you're finished head through the door and step on the switch to open up the door with your first party.