Pokemon Diamond Version

FireRed move tutor.

Emerald Battle Frontier Move Tutor (South of Battle Dome) for 24 Battle Points

There are a few ways: the easiest is to have someone hack you one, the second is to have someone edit your blissey, the third and fourth is to have a firered of emerald game, use the move tutors in that game and then transfer over via palpark.

The legit way to do it includes transferring a Blissey, that was taught Seismic Toss by the Emerald Move Tutor(Battle Frontier) or Fire Red Move Tutor( In the Back Section of the Pewter Museum), through Pal Park to your Diamond Version.

you could most probably trade with your friend with a sapphire ruby or emerald game.ask them to go yo a move tutor in fallabor town and trade your blissey back.if your game is sappire emerald or ruby go to fallabor town (make sure you have a heart scale) look for the move seismiic toss.if you have diamond and pearl game maybe find a TM or I have no other idea.