Uh...well I'll be playing Black or Gray Version primarily on a Nintendo 3DS once I'm able to get one... I had to skip the DS handheld, so I'll probably be joining in Generation V with the new 3DS release. It'll also help me prepare just in case Gray Version and/or RS remakes are 3DS-exclusive. I was also considering getting a DS Lite for the sole purpose of transferring Pokemon from Generation 3 via Pal Park...so if my 3DS happens to konk out (which should be highly unlikely, I hope), I'll be playing Pokemon games (Black, Platinum, and HeartGold) on a DS Lite.
(though the original DS "Phat" model is discontinued, I would prefer getting that over a DS Lite due to it being more durable, from what I've heard. But there's that pesky Power Button placement...)