Jeez, fanboy. You're far more articulate than I ever realized. I've encountered you around this joint many a time and never noticed your skill with words. Your article was very well written. I appreciated how you had a side note to explain every single topic you touched on, regardless of it's significance. I have a question though. - How come you're not running any stadiums? Just being able to get rid of one your opponent is using can be a tremendous help.
I'd like to say "Thank You" and then address the Stadium point.
Stadiums, for the most part, are a metagame call. I dislike them in this deck.
You don't really have the space -- you could argue that the 3 Energy Pickups are "flex" spots, but if I'm not running those there are other cards I'd want to run first.
Stadiums get readily countered. Yeah it'd be nice to counter BTS/Moonlights against decks that depended on them, but how much utility would I get out of them? Albeit, sometimes, it can be a huge leg up.
Lastly, however, is the issue of Flygon. It's a favorable matchup. Why would I do anything to make it less favorable? The potential attach an Upper and Sand Wall out of nothing on board could pose quite the problem. Given that Flygon is a great deck for making Top Cut (albeit not winning the whole bag).
What would I run?
Galactic's HQ - evaded by Spiritomb. Given the number of times my opponents went Baltoy-Darkness Grace-Claydol, I'd whiff on it being effective on the most desirable target.
Sunnyshore - what resists electric that is big in the meta? Flygon and Nidoqueen. I don't want to hand any favors to Flygon, and Nidoqueen I should be punching with Uxie X for OHKOs, in general. She'll heal off the 60 damage down to 40 anyway, without resistance.
As for what hits Luxray for weakness, there are two main answers ran. Toxipromo, and to a lesser extent, Mankey. The most common three decks, excluding mirror, to run these are Dialga G, Palkia-lock, and Gyarados. Dialga G can afford to run stadiums because it can lock them in. Gyara runs BTS like it's a treadmill. Therefore, Sunnyshore would only have lasting value against Palkia-lock, which is rarely played.
And, I'm late for class -- long story short, with EPU they're not dead once you go down an attacker or have to retreat out of say an Azelf start. It was a concern, but they were worth the lulzy benefit.