Things You'll Need
Instructions
Capture Magneton in the Safari Zone or Cerulean Cave, if you do not already possess it. Alternatively, capture Magnemite along Routes 6, 11, 38 and 39, and then use it in battle until it evolves into Magneton at level 30.
Insert "Pokemon Diamond," "Pokemon Pearl" or "Pokemon Platinum" into a second Nintendo DS, controlled by a friend. Place "Pokemon HeartGold" or "Pokemon SoulSilver" into your Nintendo DS.
Trade Magneton from "HeartGold" or "SoulSilver" to "Platinum," "Pearl" or "Diamond." Both players should travel to the bottom floor of the Pokemon Center and speak to the Wi-Fi Club representative there to bring up the trade screen. Your friend should then accept the trade to receive Magneton. Save your game.
Travel to Mt. Coronet, which is located in the Sinnoh region of "Pearl," "Platinum" and "Diamond." It is to the south of Route 217 and to the north of Route 207. Use Magneton repeatedly in battles until it levels up while inside of Mt. Coronet. When it levels up, it will evolve into Magnezone.
Return to the bottom of any Pokemon Center. Your friend should do the same. Speak to the Wi-Fi Club representative again to enter the trade screen. Accept the trade to receive Magnezone for your copy of "HeartGold" or "SoulSilver."