Well, I just cleared Stark Mountain (and collected my Heattran) in Platinum, and I must say, the Battleground is pretty nice. I like how Platinum gives you a lot of nice places to train your pokes; allowing you to take on Gym Leaders and the like at much higher levels is a really nice training method.
@Tickle Buffalo: BTW,
this is an example of how my team performs in its environment, if you were curious.
At least Pokemon tiers are more "measurable" than other titles. But when most people think of that they think of the difference between Uber and OU. Gauging the difference between OU, BL, UU, and NU, that's a whole other beast.
Pokemon is one of the few games where I feel it is necessary for a tier list to exist. FIghting games have them as well, but they usually aren't that important; most characters tend to be useful barring joke characters.
However, the mechanics of Doubles, ignored by the tier-rankers, can change the game drastically (easiest example: Wobbuffet; broken in Singles, worthless in Doubles). While true to a lesser extent in Singles, it is many times more true in Doubles, that a Pokemon's strength on its own is nothing compared to its synergy with the rest of its team. I've seen UU teams that can trash Ubers, especially after a bad prediction.
Yeah, I've seen some pretty funny stuff done with UU teams on Doubles. Regigigas for example, is NU normally. However, with some good Skill-Swapping, he gets turned into a KO machine.