Okay This is a battle of the 3rd Trio members. They are (Or at least Rayquaza and Giratina are) the Mascot of the 3rd Game (And Let's face it Kyurem is going to be Grey's Mascot) Are Dragon type and Have little plot in the original pair
You know the deal... who'll win? Who has the better Design ect...
Kyurem wins easy... He and Rayquaza have the same speed ad Defense stats though Rayquaza has higher attack while Kyurem has more HP. But Rayquaza has an unfortunate 4x's weakness to Kyurem.
Giratina get's the axer then. Kyurem's attack due to his Defense though higher then oRayquaza and Kyurem is lower then Kyurems attack. and is also weak to Kyurem's Ice attacks