Pokemon related question (Can you catch em all still?)

I was wondering with the new Diamond and Pearl games out, can you still catch em all? I know you can trade your pokemon from the GBA versions, but can you catch em all with just the GBA games and diamond and pearl, or do you have to also trade up pokemon from the GBC games up to your GBA games and then up to your DS?

I am very curisous, I use to be a huge pokemon fan, loved the games longer than the show, but After Crystal I started to focus more on shooters and whatnot and never got back to Pokemon.

Oh so you can catch them all? I thought the only way to get them all was to trade with other players from older pokemon games.