For future reference the next time you have a question ask it in the Help thread sticky at the top of the section.
Anyways, there's two ways - either trade between HGSS and D/P/Pt (which means using two ds's - if you don't have another try borrowing one I suppose?) or the risky method which needs access to nintendo wifi - put a Pokemon on the GTS once you hit Goldenrod and trade with 'yourself' on the other game quickly before someone else happens to trade that Pokemon. Mind you you'd have had two badges by the time you can do that...
That's basically it, so going to close.