here's the thing. In Gen IV, it is not possible to breed a chansey with seismic toss. I have checked and rechecked and no pokemon in chansey's egg group can be made to pass it on chansey. I even checked websites with egg move calculators. So, sorry but it can't be done as far as I know. How about just a calm-natured chansey?
Well my personal one is mild natured. I would be breeding it for you with my dittos. And no, the chansey's don't have seismic toss, though you could breed for it (i have three, one relaxed, one careful, one docile)
I can offer tyrogues, omanyte, aerodactyl, spiritomb, feebas, cubone, larvitar, relicanth, beldum, golduck, chansey's, happiny, farfetch'd, hippopotas, etc. If you don't want any of these, tell me what kinds you want and we can work something out. Also, would the elekid/magby have magmarizer and electrizer? I am also interested in a swinub, slakoth, houndour, pinsir, zangoose, and starters.