The thing about IVs are that they are completely random, period. No Pokemon can exceed 31 IV points for any one stat. Secondly, Kyurem, as well as any other legendary Pokemon, have a low catch rate, so they are all relatively difficult to catch. Lastly, you do not catch Kyruem in its new Black/White form. You must first catch Kyurem and then Reshiram/Zekrom within the game, and then the two will fuse together.
Next time, use the Quick Questions thread at the top of this section.