The Sublimely Magnificent Quinta-Bahamut Doc Shot Mark III

What you need:
Classes:
- Mime
Skills:
- !X-Magic
- !Time Lv6
- !Summon Lv5
Spells:
- Quick
- Bahamut
Equipment:
- Anything that boosts your magic stat
- Goldpin Helmet (cuts MP use to 50%)
Other stuff:
- Master the Summoner class to get the best magic boost possible
- Use Lenna for this move (she has the highest magic stat)
- plenty of ethers and elixirs

What you do:
Before battle:
- Make sure you have everything you need
- Put the three abilities on your mime and equip everything else
In battle:
- Use !X-Magic to cast Bahamut, followed by Quick (you MUST cast Quick AFTER Bahamut)
- On each turn given by Quick, use !X-Magic to summon Bahamut twice.

The results:
Now, you should have cast the ultimate spellof FFV a total of five times in one turn. Depending on your level and magic stat (Bahamut is an armor-piercing spell and ignores the enemy's magic defense stat), the damage on one target will be very close to 9999. This means that to a single target, you can do nearly 50,000 points of damage to each target on the battlefield. Of course, this will have depleted almost all of your MP in doing this (you might not have enough to complete it in some cases). This is why I suggest the Goldpin. You'll need another character to feed the caster ethers and elixirs (I'd suggest a Chemist or somone with the Medecine ability), because your Mime won't be able to equip the !Item ability. It should also be noted that this move CANNOT be mimed.