Actually, I've managed to keep pretty much all the pokemon I really like on my team whilst playing through White.
I did have to put my Serperior in the box (everything he could do - namely, grass attacks - could be done with my Cinccino and its Grass Knot), and my Zebstrika eventually got switched out for a Mienfoo. I'll probably be switching out my Scolipede for a Deino once I find one. So for me it's less 'I can't use this one' and more 'here's one that works better with what I need'.
And then there's Maractus, which I find adorable but have absolutely no use for (aside from perhaps putting it in my hack, perhaps).