Achieved reqs some days ago, so I may as well post my thoughts on the suspects...
If you use Deoxys-D, it is extremely likely that your opponent will have to deal with at least two layers of hazards for the majority of the match, maybe even more in case he/she lacks something that can 2HKO Deoxys-D without being severely crippled in the process or that forces a lot of coin-flips. These are, basically, Bisharp, Aegislash, Landorus-I, CB Tyranitar and Mawile-Mega. Bisharp can't handle Superpower variants, Aegislash must be wary of being switched out to something that gives Deoxys-D free turns by Red Card, same goes for Mawile-Mega lacking Knock Off. CB Tyranitar is not common and will end up locked in Crunch against non-Red Card Deoxys-D, which is basically begging for Mawile-Mega to come in and set up or for Keldeo to come in and launch a powerful attack. The only usable Pokemon that usually limits Deoxys-D to one layer of hazards is Landorus-I, which deals an average 55% with a Timid Earth Power. Deoxys-D is not frail, and it can come back against anything defensive/passive on the opponent's team. This is an issue for balanced/bulky offensive teams, as multiple layers of entry hazards through a match will effectively lower their capacity to switch-in on the ridiculously powerful threats abused by HO teams, this being one of the advantages in these playstyles. Recover variants are specially dangerous in this kind of matchup, as Deoxys-D's entry hazards will keep weakening the opponent's team and will eventually force its Defogger to take action. This can easily be taken advantage of by exerting offensive pressure, eventually wearing the Defogger enough so that it can be defeated. If Defog isn't used, the opposing team will probably not be able to handle the absolute spam of powerful moves used in HO teams. This not only unbalances Hyper Offense vs. Bulky Offense matchups, but even HO vs. HO matchups. A battle consisting of HO team A vs. HO team B relies heavily on the lead matchup and may end up being decided by it. If A leads with Deoxys-D and B leads with something that has unfavorable matchup against Deoxys-D, B is essentially at a disadvantage right from turn 1. If both A and B lead with Deoxys-D it is literally a coin-flip, and the one who wins it starts the battle at a great advantage.
About hazard removers: the only common/relevant ones are Latios, Latias, Mandibuzz, Excadrill, Zapdos and Skarmory. The Lati twins are extremely vulnerable to Bisharp even if they run Hidden Power Fighting/Fire, since Bisharp forces numerous gambles and has a great chance of removing them from play or at least being defeated and avoiding Defog. Defiant Thundurus is vulnerable to LO Draco Meteors, yes, but just like Bisharp, it is in profit as long as it either avoids Defog or gains a Defiant boost. Again, Latios and Latias are not 100% reliable against HO teams because they force numerous gambles that are usually favorable to the Deoxys-D/Defiant user. Mandibuzz and Zapdos are very susceptible to great offensive pressure, specially from teams based around a "Dual Genie" core being supported by Deoxys-Defense. Mandibuz gives free-turns to Mawile-Mega, which is always a bad thing, and will probably end up seriously weakened by Bisharp to the point it can't do much in the match after that (Life Orb Bisharp wins one-on-one as long as it switches in on Defog). Physically Defensive Zapdos has a great chance of being OHKOed by a +2 Knock Off from any Bisharp variant after Stealth Rock and 68 SAtk Zapdos has a very small chance of OHKOing 0/4 Bisharp with Heat Wave. Zapdos' walling potential is also seriously crippled even it if ends up defeating Bisharp, and many teams rely on a healthy Zapdos to check threats such as Pinsir-Mega. Both Zapdos and Mandibuzz fare poorly against Defiant Thundurus, either attacking and not removing Deoxys-D's entry hazards OR ending up against a +2 base 125 Attack with 111 base Speed and a resistence to common priority. That's something no team in the world enjoys facing except for ones with Quagsire (which is Deoxys-D setup bait!). Skarmory also doesn't do well against Bisharp and Thundurus, once the best it can do it retaliating with Counter. This will leave Skarmory severely weakened and unable to do anything else in the match. This is specially harmful if one depends on Skarmory to deal with Azumarill or Mawile-Mega. Ironically, all the aforementioned Defoggers are either crippled by Thunder Wave or hate being Taunted by Deoxys-D itself. The Defiant users clearly aren't the problem here. It is Deoxys-D's ridiculously consistent, durable and fail-proof hazard setting that forces all of those gambles and puts the player fighting Deoxys-D on a disadvantage.
While Excadrill can work against teams lacking Balloon Aegislash, nothing besides Deoxys-D actually gives a turn for Excadrill to Spin unless it is in the Sandstorm, and even if it choses to spin, it usually forces 50-50s against Mawile-Mega, Thundurus and Landorus while flat-out losing to Azumarill and Keldeo, all extremely common on HO teams.
Deoxys-D's ability to, when used right, force numerous game-deciding gambles and provide consistent offensive support with very little to no cost at all is what, in my opinion, makes it an undesirable presence within the OU metagame. Will post my thoughs on Deoxys-S soon since I don't want this post to be even larger.
and Deoxys-D shoudn't be setting up screens at all!