Mega Gardevoir
3 -> 2
With speed control, and a bulky spread Mega-Gardevoir becomes quite difficult to KO. It can usually 2HKO the majority of what's in front of it with Hyper Voice, and can be quite difficult to stop due to the majority of the meta being special attackers. Gardevoir's base speed of 100 make it quite easy to drop EVs from Spe, and put them into its defensive stats.
This nom doesn't say anything about why Garde should be in Tier 3 instead of Tier 2. You just described why it's a good Pokemon without describing what about the metagame has shifted deserving its movement up. If anything, our recent metagame shifts made Gardevoir worse, not better, as we gained two Megas that both switch into and set up on or OHKO Garde and a Steel-typed Trick Room setter that does the same thing.
Deoxys
5 -> 3/4
I honestly don't know why this was Tier 5 in the first place, as it really does the same thing its counterpart does in DOU. Psychoboost obviously OHKOs the majority of the tier, minus those that naturally resist it.
Deoxys does not OHKO the majority of the metagame, that's a gross overestimation of its power. It's tier 5 because that's where it belongs. It's frail, duh, hard to fit on teams, and the abundance of psychic resists in Metagross, Garde, Zong, Scizor, etc, etc makes it difficult to just "blow everything up" at will.
Hitmontop
4 -> 3
Hitmontop's kit is amazing. Fake out, Feint, Close Combat, Helping Hand, Wide Guard, Quick Guard, and more make Hitmontop extremely difficult to predict, which makes it really easy for Hitmontop to do its job.
Hitmontop literally always runs Fake Out/Close Combat/Wide Guard/Feint or Helping Hand. How is that hard to predict? I always know what Hitmontop is doing when I see it on my opponents team, if anything it's a testament to how good Hitmontop is as a bulky Fake Out user/support mon/pivot. It's in tier 4 because of its lack of offensive presence AND its predictability. It doesn't take a Kaori level player to protect on a Fake Out.
Azumarill
1 -> 2
I've noticed Azumarill being less common, and have even struggled to make it perform as a Tier 1 threat should. With the introduction of Torkoal, it becomes much more difficult for it to be threatening with Aqua Jet due to Drought.
Torkoal, while I will admit is probably better than Tier 5, is not good enough to single handedly drop Azumarill (which has been the best pokemon in this format since its Gen 7 inception, only to be challenged recently by Metagross). Azumarill is not 100% reliant on Aqua Jet to damage things, although that's obviously the move that makes it exceptional. It's generally always paired with a redirector, and having the priority to weaken Torkoal Eruption + heavily damage it's Trick Room partners, makes any TR player fret about their gameplan while facing down an Azumarill.
AbsurdityNL
Maybe I'm misreading the tone of your post, but I think declaring Torkoal + Lilligant "broken", or even problematic, after admitting you have 2 days of Doubles UU experience (and I can only assume that experience is on our notoriously difficult ladder) is jumping the gun by quite a bit. Ignoring the fact that Politoed + Ludicolo dunks on that combination, a lot of doubles players, especially in our tournament setting, have been playing versus LilliKoal on DOU and DUU's low ladders for a good part of 18 months now, so they've got a handle on playing against it. I don't mean to bad talk the combination, or say it's unviable - as it certainly is viable - but I would just urge caution before making declarations about the state of a metagame before having more experience.
The above is a point I really want to stress to everyone - the ladder metagame and our tournament metagames for DUU are vastly different. I try not to even test tournament teams on the ladder, because I'll just lose to Masquerain or something and scrap it. I would encourage everyone to try to form a more developed opinion on DUU - and only a fraction of what you can learn comes from me and this thread. Guys like Demantoid, Lord Death Man, Memoric, AuraRayquaza, and I could go on, have done the metagame so much good by developing the tournament metagame and finding new ways to win and push the boundaries. Winning on the ladder has never been a good measure of DUU success, and I would urge everyone to look to the circuit and other DUU tournaments to make judgments of the metagame. Sorry if this post comes off as condescending or know-it-all-ish, I did not intend it to be.
Oh, also please provide an explanation when making VR nominations. Just saying "x mon should be in tier y" doesn't help anybody understand why you feel that is the case.