Silvady's ability being called "AR System" seems to further confirm its connection to Arceus. It'll be interesting to see if Arceus actually plays into S&M's plot. It's 3 generations removed as a legendary, but it's one of those pieces of Pokemon lore I've always enjoyed.
Edit: Also I forgot in all the craziness, but Type: Null evolves? That's pretty weird in itself, eh? Assuming it's still a legendary, and this isn't some other kind of form change, this would be a first. There's no way a level-up evolution would make sense with the story, so maybe it's based on happiness?
I go back and forth on the Jangas. I see how some can say they're over-designed. They would have been really difficult to render in earlier generations of Pokemon, and now that GameFreak can work with more complicated designs, it doesn't necessarily mean they should. But maybe they're going for a samurai mail armour vibe, and so the amount of rings/plates was necessary to communicate that idea.
My main complaint is that Jarango is so similar to Jararanga - I feel like it should have had a more round and sturdy form as a middle evo, like a Shelgon. But maybe they felt they just did that with Quilladin and didn't want to repeat themselves. They also feel a bit generic as the pseudo-legendary dragons - the Goodra and Hydreigon lines are really distinct, but this one is more like a counterpart to the Haxorus line. Even the colour scheme is similar to Haxorus. And I wish they had kept a more ankylosaur shape, but again, we already have Torterra. And they're yet another line that goes from quadrupedal to bipedal. But overall, they're growing on me.