I can tell you that the only certified engine for North America right now is the 250. We'll not be getting the diesels because EU-6 standards are not as strict as US, and making them comply would cost a ton of money.
The low powered versions of the gas engine won't be coming to North America either, at least not initially.
How do I know? The B250 has been sold in Canada for a few months now and that is the ONLY drivetrain - 7 speed DSG and 208 net HP engine.