Alright, so as we all know, the first member on our team is really the deciding factor in what the rest of your team should be, and thus, is quite important. Starting off my theorymon'd team, here's my starter:
#1: Pokabu/Emboar - http://www.serebii.net/pokedex-bw/500.shtml
I've chosen the fire type for every generation for my first run, except for GSC (Chikorita <3), so the trend continues; even if everyone is saying the Water starter will be the best in-game. Being the aggro, all-out offensive player I am for EVERY game, strategy games like pokemon included, a Fire/Fighting type is definatly my style. Great attack stat, great HP, and a sufficable movepool (so long as I can find Brick Break in-game quickly... ), I thought I'd give Pokabu a try. And if not... BACON! =D
#2: Mogurew/Doryuzuu - http://www.serebii.net/pokedex-bw/530.shtml
I next to never use Ground types very often on my in-game runs, or steel types since they aren't as aggro as I'd usually prefer. Doryuzuu takes the defensive stereotype of the two types and drills (someone had to make the pun...) right through it. A brutal max attack stat of 405 and great HP, as well as some grand resistances (and weaknesses as well...) make it an interesting poke. A lot of people would probably wonder why I don't use the Ground/Dark crocodile poke, but I'd rather use Doryuzuu for it's steel typing, superior attack power, and what I see as a better movepool. Keep it unevolved and you get Earthquake at lv. 33; sign me up. Rock Slide, Metal Claw for STAB, and plenty of TM options make me think Doryuzuu will be a functioning team member.
#3: Terrakion - http://www.serebii.net/pokedex-bw/639.shtml
This slot was really questionable, but I was thinking about throwing in a legendary here for just my first run; either the legend of my game (as late as you get it), or the Rock/Fighting type Terrakion, caught almost as late at Victory Road. I'm interested in these three whatever-animal-legendary fighting types, and since I've already got a Steel type, I'll go with this guy. Epic all-around stats, a nice movepool, and an absolutely fantastic ability if you can take advantage of it, I severely doubt he would dissapoint unless he's highly underleveled by the time you catch 'em, which I doubt.
#4: Kibago/Ononokusu - http://www.serebii.net/pokedex-bw/612.shtml
This thing is the Garchomp-esque Dragon Dance sweeper I mentioned earlier; look at the base stats and stare in absolute terror. Easily enough speed and MASSIVE attack to abuse Dragon Dance. Defenses not too frail to let it die immediatly. Mold Breaker to abuse nothing more than a Dragon move and EQ for perfect coverage (except for Skarmory and maybe a new poke, but... details). Draco Meteor to screw with said Skarmory (if this thing got Fire Blast...). Can Skarm even take a +1 Outrage more than once from this beast? And what if it just runs D-Dance, Dragon Claw, Taunt, and Earthquake? No phazing, no walling, no winning for you. BEAST.
And in-game, this thing can be caught at lv. 31, and evolves promptly 7 levels later, and again at 48 into this beast. I never run dragons in-game since they take so long just to evolve (don't say anything about #443 -.-), but I feel I can catch this thing at a late enough level to make use of it, so I'm definatly going for it.
Speaking of that, for those who want to know why I won't use the Dark/Dragon poke, it's useless until it's final evolution, which comes at lv. 60. Ugh.