Need to find a dress.

[False Prophet]

Want to get a nice dress for my companion. was thinking about item coding it. anyone point me to a legit way?

[Eternie]

Formal dresses can be found in various casinos. If you gamble in them and start winning you may get a key to stay in highroller suite of that casino. Veronica will be quite excitied if you give her a dress.

Of cousre there are lots of homes or vaults you go through that have Pre-war outfits which will be a dress if worn by a female

With the mod JIP companion Control you can also select which items they wear

[Bansheebutt]

Most people will find themselves with some extra formal wear during a quest in the Ultra-Lux casino.

[*Logan*]

I've never though to actually go looking for a dress, but I have collected several of them, and most of them have a nice agi +1 perk.
I have seen pink and green dresses and I often use a green pre war dress around towns and non-hostile areas for that agility +1 boost.
It's safe to say that you will find them in drawers, dressers, etc in various towns throughout the game with minimal effort.
Just check houses in early areas of the game such as Goodsprings and Primm.

[Malvastor]

You also find a very nice one near the end of Dead Money. Though that's a lot to go through for one dress.