I don't think so. You'd have to buy black or white. You can transfer Pokemon from Diamond to Black/White, but not the other way around. We'd have to get lucky and get matched up, too, I don't know of any way that you can battle/trade with a specific person except when you're by them in real life with infrared or wireless or whatever.

And Pokemon Diamond/Pearl had some of the best pokemon ever. If we're going back in time, though, I'd pull out my Zapdos. He's a monster with his 383 special attack.