Questions about Pok�mon Soul Silver and Pearl?

I have Pok�mon Soul Silver and I was thinking of buying Pearl. If I have both games, can I trade pokemon between them using one ds or not? I do have wi-fi, if that makes a difference. Also, can I breed Jigglypuff with Haunter? I am hoping to get a ghost Pok�mon that knows mean look and sing to make it easier to catch legendaries.