Things You'll Need
Instructions
Teach your Pokemon Seismic Toss through a Generation III "Pokemon" game. Since Seismic Toss is not a TM in Generation IV, which includes "Pokemon Platinum," it can be difficult to acquire the move in this game. Load up a game of "Pokemon FireRed" or "LeafGreen," which are both on the Game Boy Advance and thus playable on the Nintendo DS, and fly to Pewter City. Once you get there, walk to the move tutor's house, and ask him to teach your Pokemon Seismic Toss. Choose your target Pokemon carefully, as the move cannot be taught more than once. Go to the Pal Park on Route 221 to transfer your Pokemon to "Platinum."
Level up your Pokemon. Pokemon normally level up by engaging in battles, be they against wild Pokemon or a trainer's Pokemon. In "Platinum," the legendary Arceus is the only Pokemon that will automatically learn Seismic Toss by leveling up. However, you can use the Pal Park again and trade some Generation I and III Pokemon to "Platinum" so as to level them up and get Seismic Toss. Generation I Pokemon vary widely upon when they learn the move. Mankey will acquire it at level 33, Primeape at 37, Machop at 39, Machoke at 44, Machamp at 44 and Pinsir at 25. Two Generation III Pokemon --- Makuhita at level 46 and Hariyama at 51 --- can also learn Seismic Toss this way.
Breed two Pokemon. In "Platinum" you can breed Pokemon so as to produce special offspring. If the father is a Primeape or Mankey and the mother is a Teddiursa or Miltank, the offspring will inherit the Seismic Toss ability.
Trade one of your Pokemon for one of your buddy's Pokemon that has Seismic Toss from "Pokemon Platinum," "Diamond" or "Pearl." The Nintendo DS is easy to trade with, so long as both players are willing to share their Nintendo Wi-Fi IDs and have Internet access. Write down both of your numbers and user names in the Pal Pad, and then proceed to a Pokemon Center to trade. Open the Pal Pad through your main menu by clicking on your "Key Items" list. The Pal Pad will prompt you to write down both the name and number of your friend. Talk to the Wi-Fi Club lady in the back of any given Pokemon Center, and wait for her to connect you to the Nintendo Wi-Fi network.