Let me see if I can get this right, lemme know of there are some holes or mistakes in this Ze.
We basically concluded that there would be shiny distributions for Reshiram and Zekrom as Grey is hits the streets. These shiny versions of the Pokemon would play a role in obtaining Kyurem in Grey. The distribution or event would most definitely be WiFi so as to include everyone. Hell, the even could be ingame at some point and force the beast to be shiny. Either way.
The power generated from the tails of Zek/Resh appears to be fainter in their shiny versions than when compared to the normal sprites. Ze found this to be interesting and plays into how this would effect the storyline and is indeed a nice touch assuming this is all correct.
We know that, based on deciphering the code from the underwater ruins, Kyurem can be taken to be the King. It represents a culmination of Resh/Zek in mythology. Kyurem was essentially whole and then split apart again. What's left behind is the exoskeleton we have in BW. It appears dead, and its tail is fractured, as if the generator that was once there has been removed.
Having a hard time how the two brothers played into this but they either took Kyurem and remade Resh/Zek or used them both to reassemble. idr how that went. There's also some stuff about how Kyurem befriends one and conquers the other. Will get to this in a second.
The point is, in Grey, the shiny versions of Resh/Zek appear to exude less power, which we could take to mean that they are weaker. In the story, we have N and you as the two primary characters; both of which parallel the brothers of Isshu's mythology. Using the God Stone (possibly King Stone) it will be N's objective to awaken the beast (at some point a selection will occur wherein you end up w/ Resh OR Zek and N obtains the other). This is important, later. The God Stone will drain the energy from both Resh and Zek culminating in the revitalization of Kyurem.
Kyurem, it is suspected, will end up having three formes (topping Sinnoh's Giratina by one). The forme we have now, a forme which indicates Kyurem has befriended Reshiram and a forme indicated it has befriended Zekrom. Selecting one of the two legends is important as it not only determines the forme of Kyurem but also the move it will know. For instance, in BW it learns Frozen World. A fairly weak Ice attack (65 base power) that is also guarenteed to lower the opponent's speed by one stage. But, there are two Ice attacks we know of in the game's coding, which no one learns. Their effects follow and shed some light on all of this as well:
Cold Flare wrote:Inflicts regular damage. Charges for one turn. Has a 30% chance to afflict the opponent with Burn.
An Ice attack which exhibits the effects of a Fire type attack, aka Reshiram.
Freeze Bolt wrote:Inflicts regular damage. Charges for one turn. Has a 30% chance to afflict the opponent with Paralysis.
An Ice attack which exhibits the effects of an Electric attack, aka Zekrom.
It is entirely possible that Kyurem will learn the move based on what type-base is the opposite of the legend you end up choosing. This has meaning because we already know that Zekrom and Reshiram attacking together (when using Cross Thunder/Cross Flame respectively) create a new effect (see the starters' combo 'Oath' moves).
So, it should come to pass that N awakens/recreates Kyurem, which angers it and leads to its opposition to N's selected beast. You, the protagonist, find yourself in the position of controlling the beast that Kyurem favors. From here, it could be a matter of you catching Kyurem in order defeat N (ala BW's plot twist) or a more standard defeat of N and then later meeting w/ Kyurem in the forme you put it in.
Quite a bit to take, I'm sure, but these seems to work well with the mythology demonstrated in the undersea ruins, the revelation of non-shiny legends being forced upon us, and utilizing the known effects of unique (more powerful) Ice attacks that surely will belong to Kyurem at some point as well as plot-twists brought about in Gen4 and Gen5. It does not explain why Victini and Kyurem can't be shiny as well Resh/Zek but there will surely be future events to explain it as well and perhaps differently than Ze and I concluded. Either way, its a sweetass plot we've got up there :D