You can pretty much get by with just the Gunner, Dark Knight, and Alchemist dresses. Berserker is great in the Via Infinito for fighting those big dragon creatures that stalk the halls (can't recall the name at the moment.) And the Lady Luck dress is great for collecting items, money and experience. This is especially useful for that one insect infested dungeon where you need to fight the insects for explosives to continue. With three Lady Lucks instead of getting 1 bomb you get 8. And if you were going to receive 3 you would get 24. Quite a time saver.

To expand on the Berserker strategy: When you master berserker (or get close to mastering I don't have the list of skills and prerequisites with me) you can automatically dodge and counterattack. So long as it is not Oversouled your berserkers will automatically evade and counter every attack. You don't even need to fight, though I suggest either using Berserk on all three or holding down "X" and switching your TV from input to your favorite show for a few minutes.

But outside of those few I haven't found anything exceedingly useful, though I have mastered every dress sphere other then Mascot. I hear that is useful, I never got a lot of use out of it.