Questions on trading pokemon in platinum.?

I have a few questions.I have pkm platinum and Sapphire.I want to trade some pokemon from Sapphire to platinum.How can I?I know about using the pal park thing...but I haven't beaten elite 4 yet, so I cant migrate.That means I will have to use the Nintendo wifi thing.I do have a wireless router thing, so can someone give me a link on how to connect internet to my DSi? My sister has a Ds lite, will that effect the compatibility if we try to connect with each other,can she connect to internet?Also I want to evolve haunter to gengar and magmar to magmortor(if that's how you spell it) does that mean i need to trade from someone who has pkm Diamond or pearl?.Can someone help? I will really appreciate it.My pokemon are ok its just I think I can to better.