Erm, am I not explaining this right? I feel like I've been as clear as I could have been..
You can't use Powersaves on NDS carts, period. BW Save tool requires saves from NDS carts. It won't magically connect to Powersaves.
a) that's not the problem
b) the bin file made by Powersaves is a type of save file; it's a encrypted save file for the 3DS.
However, even if we remove that, you can't use Powersaves on NDS carts.
Pokemon Black, White, Black 2, White 2, are NDS carts.