Man do I love you guys! (and girls, shadow cresselia)any question I got..

Ok not sure about where to find one but it think it's on wild Pokemon but I'm not sure...

And to evole you must trade while holding the scale.

1. Once you've obtained the National Dex, you can find it attatched to some wild Horsea and Seadra, both found on Route 230, or Dratini and Dragonair, rarely found in the room with the waterfall in Mt. Coronet. To run into either of the four, you must use the Super Rod.

Another thing: Dragon Scales are always found on wild Horsea, Seadra, Dratini, or Dragonair, but it is possible to sometimes run into one of them holding one. You also don't need to catch them, you can use TM46 Theif, and if they're holding one, then you'll steal it. If they're not, you won't recieve anything.

Since Horsea and Seadra are much more common than Dratini and Dragonair, start with them, first. If you would like a Dratini/Dragonair/Dragonite, then start with them.

2. You have to trade Seadra while he's holding it to evolve him into Kingdra.

3. If you don't like the fact you can only find it on wild pokemon, then you're out of luck, because you can only find the Dragon Scale on wild Horsea in Emerald and Sapphire.

Hi, the dragon scale can be found on wild horsea, seadra, dratini and dragonair, but only after you got the national dex.
Hope this helped,

Shadow Lugia

Aww... Ok, You must catch a horsey. They carry it sometimes. Just catch a bunch of the little blue things. If one holds it, good for you!!! If not, keep trying. If you don't want to keep the little dudes, release them or trade them to me (Just kidding!).

-Shadow Cresselia

To get a dragon scale catch horsea. Some of them may be holding a dragon scale. 1 out of every 10 maybe. Yes to get a kingdra trade a seadra that is holding a dragon scale.

You can get it like that in emerald and sapphire to.

If you want a dragon scale just get a bunch of horseys and pooooof you have a dragon scale.

Well, actually, there's no easy way to get a Dragon Scale. You can only find it when you catch a wild Horsea, Seadra, or Dratini that's holding one. For the 2nd question, you do have to have Seadra holding it, but it must be traded( and traded back if your keeping it).

-pokeking

Well actually I'd never given it much though, but I remember something about it. Some wild dragon Pokemon may have a dragon scale. So go out to a place were you know dragons are common and use thief till you get it.

You get dragon scale in diamond only by finding it on a wild horsea, seadra, dratini, or dragonair. And to evolve I think you have to trade while holding that item

Use theif or that swaping move on a wild luvdisc, dragoinar, dratini or any other Pokemon that are dragons.