Well, I need to play through B/W a bit more (read: actually beat the Champion in White) and get more familiar with the region before I can actually try challenges. It will be slower going, as No$gba isn't up to speed with the new generation (not as fast or smooth, especially on the cutscenes), and the challenge ends later - much like a HG/SS run.
Anyway, I was thinking about finishing a few of the ones I have already first, like the flying/normal ones. It's unfortunate that you can't get any pre-Unova Pokemon until after you beat N, although you do get them at very high levels, and the Lucky Egg is a great boon. I will say that not using the Amulet Coin = no vitamins = lower stats, which is kind of lame (on top of fighting less Pokemon leading to less EVs in general).
So which UMC should I do next? the Steel and Dark ones don't require Kanto, right (LG/FR)?