Black 2 PWT help

So, I'm kind of struggling in the post game PWT. I have great pokemon that I've transferred from previous games. Dialga, Palkia, Arceus, Giratina, etc. Unfortunately, I lack pokemon to use in the PWT. I always find myself with either a crippling Dragon/Ice weakness, thanks to my personal favorites Salamence and Dragonite, who I got on the GTS, or I end up with a horrible Ground weakness because of my reliance on Heatran and Lucario. What should I add to nullify these weaknesses? I have Latios. I have Ninetales. I have Cobalion/Terrakion/Virizion but I haven't trained them. What do I need to add? What do I need to take out? Should I try and find something on the GTS?

you should get an exp share and give it to the one you want go to the elite four and beat as many as you can!

Your team does have quite good defensive synergy already, but I think that two Dragon/Flying types are not necessary. I think that replacing one with Latios may be your best bet, as not only it still provides a Ground-type immunity and a resistance to Fighting, it also has a neutrality to Rock (which two of your Pokemon are weak to so far) and an Electric-type resistance. If you're worried about Ice-type weaknesses just simply switch to Heatran, as it's 4x resistant to Ice.

OK, but Latios is kind of lacking in Special Attack and Speed. If I EV train it now, will it show when it goes to level 50 for the PWT?

Yes, it definitely will. I'd grab a Power Lens (Sp. Atk)) or Anklet (Speed) and start training at the Celestial Tower, or if you'd like a head start give it some Calciums and Carbos.

Well, it's showing for sure. Latios now has a rather high 170 Special Attack and 150 Speed thanks to Calcium, Carbos, and Join Avenue. He's definitely pulling his weight. I was worried about having two Dragon-types, but you were right. Adding Latios was definitely a good call. My current team is Latios, Dragonite, and Heatran. They're doing very well.