I think the sequal to Black/White might let you able to capture both Reshiram and Zekrom by following the squeal pattern.
Ruby = Groudon
Sapphire = Kyogre
Emerlad = Groudon & Kyogre
Diamond = Dialga
Pearl = Palkia
Platinum = Dialga & Palkia
Black = Reshiram
White = Zekrom
(sequal) = Reshiram & Zekrom? [note: its a possibility/ highly unconfirmed]
I wonder what NINTENDO will do before you face N at the Elite 4, since thats the point where you are forced to battle Reshiram/ Zekrom at that tower.