There aren´t many good pokemons for B/W,but i always used Weavile(wk:fire,fighting),Ninetales(wk:water,ground,rock) and Swampert(wk:Grass) After-Elite 4.
I would say: Vanniluxe(Wk:Fire,fighting) and Haxorus(wk:ice,dragon)
yea, i usually beat it with 4 pokemons, and 1-2 of them are HM slaves.
if my starter is :
serperior>something that can use fly>something that can use Surf(both, if it´s a Swanna)
emboar>same thing>same thing>some thing that´s strong to Air(Flying) and psychic.
Samurott>same thing> some thing that´s strong to grass and psychic.
in B/W2, you can get Lucario,Grumpig,flygon,Ninetales,jellicent,virizion,zangoonse,seviper,ampharos,weavile,any Eeveevolution and much more of Great pokemons.
BEFORE the last Gym.
how the f*** are you with serperior before the 4th gym....?
yea, Zorua can become zoroark, it has good speed and good attacks,palpitoad can become seismitoad, which is one of my recomendations(i forgot to add)but it has low speed, but everything is good.
i can´t say about Darumaka, because i never used him :/ and it looks Kinda.....ugly to me.
You can get ,Maractus and leavanny before Elesa and Swanna, little after her battle,on the bridge.
the Story mode is the Continuation to the main story of BW1, you´ll get lost on the references and charaters if you don´t play it before.