I just realized that I haven't caught Kyurem yet in white. I'll catch a Jolly one in White, and a Timid one in B2. I'll then use them if or when I want to make a Jolly Black Kyurem or a Timid White Kyurem. I still have my Reshiram from my Black and my Zekrom from White and Black 2 to make Black/White Kyurem.
That will work, right? I don't see why it won't.
And if I want to use a Reshiram or Zekrom I still have the Event ones. Timid and Jolly of course :)