Final Fantasy III/The Airship Nautilus

Notes for the NES version
Let's summarize the equipment you found for free in the last few quests:
 * Full equipment for Dragoon (two different spellcasting spears, armor, helm);
 * Full equipment for Viking (spellcasting hammer, armor, helm);
 * Full equipment for Geomancer (status-inflicting bell, armor, bracers);
 * More arrows for the Ranger.

The next dungeon is miniaturized, so physical attacks will be useless. Not only that, status-inflicting weapons (Earth bell, Medusa arrows) are uneffective, too. You definitely need as much magic as you can.

Keep one Dragoon for his spellcasting Wind Spear, keep the Ranger for healing, get the Geomancer for his Terrain ability. Finally, head to Replito and purchase the five summon spells for the Evoker: even the Chocobo Escape will be useful in a miniaturized dungeon. For the rest, the Evoker equips the same rods and armor parts as the Black Mage.