I'm not a BH expert by any means kirby, but the problem that strikes me here is that you have no rapid spinner, and what seems to be your lead basically invites SR setup, with no Magic Bouncers on the team. And not only do you have a pokemon quadweak to SR, but one that sets up your weather. Granted, only Kyurem-W only really relies on it, but his only other attacking option is Extremespeed, so his main attacking move's got a 70% chance-never a good idea. And did i mention you've got another SR weak pokemon?
So basically like Arkeis said, try to fit in a Rapid Spin user. Or at least lead off with something that can prevent SR going up with some frequency.
And going from there, what's up with your Kyu-W set? It's got Magic Guard and Focus Sash, and while I get that Recover is probably there to restore the Sash and such, Kyu-W can only Recover on free turns that it should be using to boost in any case-despite its bulk, its defensive typing means plenty of stuff can hit it SE, so it shouldn't be healing mid-sweep. As for Extremespeed, it's not THAT strong, and there's plenty of non-frail stuff fast and strong enough to revenge Kyu-W. Why not invest in at least one other special move, and possibly two? (And by the way, how is that set self-explanatory?) Also, instead of using Magic Guard and Focus Sash, how about just using Substitute and some other ability? (Magic Bounce would be helpful for this team)
As a final note, even though Deoxys-S appreciates the occasional Brightpowder-induced miss, each miss gives it 2 more turns of stalling. Leftovers gives it 6 more turns of stalling (4, if you can't make a sub at 25%), which basically means you'd need to get 3 misses to even the score. I don't think you'll be getting much HP back from Leech seed, since just about any legitimate attacker should be able to OHKO Deoxys-S without much trouble. (Or they'll just set heavy hazards/taunt.)
Edit: Apparently his, how did i miss that?