If they want, yes.
trade with someone who has black
Trade with someone with Pokemon Black.
trade with someone from pokemon black
No, you need to get someone to trade it to you from Pokemon Black.
There is no code you trade with someone who has Pokemon white
trade it to someone
It is exclusive to Pokemon White, you can't catch it in Pokemon Black. You would need to trade with someone who has white.
In Pokemon White you'd have to trade with someone who got it in Black/White 2
Reshiram is exclusive to Pokemon Black. You will need someone to trade it to you.
It is only found in Pokemon White, so you will have to get someone to trade it.
You will need someone to trade it from Pokemon White, as it is a version exclusive.
The only way is to trade from someone who has Pokemon white.