lol PC's are gay. Who the hell wants to sit in a computer chair while playing games? I want to sit in my awesome couch in front of my awesome 52" TV.
Nowadays its fairly easy to hook a computer up to a TV and just play games or do whatever that way. All you need is a TV with a VGA input, and most new ones have that these days...
There are probably also computers that can output their display to HDMI too, so that's also an option.
98% of people don't have their computer setup near the main living room TV(the big screen HDTV) to do a PC connection. Probably 80% of people don't even have a HDTV (27" and up) with a VGA connection on it in their bedrooms to hook a computer upto either.
I just can't see the DS2 coming out this year with Pokemon Generation 5 coming to the DS around the same time. Just makes no sense.
Wrap your brain around this.
a.) Forwards compatibility. DS games can be played on DS2, and games programmed with that in mind will have bonus features when played on DS2 (See GB -> GBC)
b.) They announced it as coming to DS because the DS2 wasn't announced yet and the DS2 is compatible with the original DS. Cart form factor will likely be the same, and the game may be backwards compatible with the original DS, yet some functions outside of the basic Pokemon gameplay will only work when using a DS2(not to mention the graphical boost).