lets say traded to diamond as origin form
No. Altered comes in DP, Origin and Griesous Orb in Pt
You could but in order to do that you would need to either use a cheat to get the item in Diamond or Pearl, or I think you can get it by trading a Pokemon in Platinum holding the item over to Diamond or Pearl. I'm not entirely sure about the second answer.
you can get them in dimond,pearl and platinum at the stone pillar and turnback cave