How Can I Get a Dragon Scale on "SoulSilver"?by Junou MathieuUpdated September 22, 2017
Some Pokemon can only evolve through the use of an evolutionary item. There are 20 such items In "Pokemon SoulSilver," including the Dragon Scale. The Dragon Scale is a thick and rare item that evolves Seadra into Kingdra. If you trade a Seadra while it is holding this item, it will evolve into Kingdra immediately. The Dragon Scale is found in Mount Mortar or at the Pokeathlon Dome.
Fly to Ecruteak City and go east to Route 42. Walk east on Route 42 until you reach a small body of water. Use the "Surf" ability to cross the water to Mount Mortar. Enter Mount Mortar through the cave entrance.
Surf west instead of taking the descending ladder. Ascend the waterfall with the HM07 ability. Surf around the land and go through the cave entrance. Go to the northwest corner of the cave. Head east of the ladder and pick up the Item Ball, which holds the Dragon Scale.
Win the Pokemon League Champion title of Johto. Speak to Professor Elm to get the SS. Ticket. Fly to Olivine City and talk to Professor Oak at the SS. Aqua. He will upgrade your Pokedex.
Enter the Pokeathlon Dome west of the National Park in Johto. Compete in the 10 events until you have at least 2,500 Suron Points. Shop at the dome on a Friday and buy the Dragon Scale for 2,500 Suron Points.