I am having trouble sucessfully getting on Wi-Fi for the DS Lite. Do I really need the USB adapter, because I thought that was discontinued?

I mainly want to get on Wi-Fi for Pokemon Platnium and Pearl for trades so I can evolve some of my Pokemon and be one step closer to actually completing a Pokedex in one of the now seven versions I own. (I know that's pathetic)

(Red, Blue, Yellow, Silver, Firered, Pearl, Platnium)

Anyone who wouldn't mine trading Pokemon back and forth or helping me trade with them would be greatly appreciated.