I think things need to be looked at in a more logical way. I'll try and break things down rationally. Here are the infamous culprits now:
--------------Latios
----Arguments to Ban:
Can OHKO most of the metagame and can sometimes simply muscle his way through his few counters/checks. A number of possible sets, all of which are very powerful.
----Arguments to Keep:
The few counters/checks it has are very popular and serve a multitude of purposes other than simply "just countering Latios". Also, he is weak to pursuit, and he requires good prediction because without good prediction, more often than not hell be firing off resisted moves on a pokemon who can come in and faint him unless he can predict the correct switch (or non switch).
-----Personal Opinion
For smart players, Latios is usually not that much trouble. A combination of good prediction, and a team with at least one of his more reliable counters (which is good anyway because his counters are all good pokemon) will do him in quite easily. I think the fact that he can OHKO so much of the metagame makes too many players hit the BAN button too fast, without examining the entire picture. I Vote No-Ban
-------------Deoxys-S
----Arguments to Ban:
Fastest pokemon in the game coupled with good stats and a ridiculous support movepool. Can support in so many different ways, that countering it becomes difficult without knowing exactly what it is its trying to do.
----Arguments to Keep:
New abilities and moves in Mischievous heart, Magic Mirror, and Dragon Tail which are pretty popular are the bane of Deoxys-s as well as most support pokemon in general. Weak to Pursuit, and despite his decent-good stats, cannot stand up to too much of anything in the form of direct hits which all results in reduced time for support.
---Personal opinion:
I'm pretty torn on this. On the one hand, killing a simple support set by one or two strong hits or by packing rapid spin and nipping the problem in the bud is pretty easy. However, such a strategy is rendered moot for sets that set up dual screens. Concordantly, countering the dual screens can be easy, but is a different strategy than countering Entry hazard support. The point is that, it can stretch a team to the point of over centralization (what this thread is about) to be able to counter both sets right. I vote Ban because i think this pokemon breaks that support clause because of my reasons (but doesn't shatter it.)
--------------Deoxys-D
---Arguments to Ban:
See Deoxys-S, but remove the speed while adding ridiculous bulk.
---Arguments to Keep:
See Deoxys-S, but remove the fact that he can't stand up to too many hits, and add the fact that there are a large number of pokemon that can outspeed him and kill him, shut him down, or neutralize him before he can do too much.
---Personal Opinion:
This is very similar to the other deoxys to me. theres just too much it can do which has it breaking (not shattering) the support clause. I vote ban.
-----------------Excadril
---Arguments to Ban:
His ability, stats, and movepool lets him become the best and most effective sweeper in Pokemon provided there is a sandstorm. And, it isn't hard at all to have sandstorm up, considering both sandstorm inducers are great Pokemon. There is almost nothing that isn't OHKO'd by him, which is further augmented by the fact that he outspeeds everything. His very few counters/checks can either be easily dealt with by teammates or simply muscled through by himself sometimes. Add to that Rapid Spin, 2 Immunities including thunderwave, being the best user of balloon, and the fact that he is resistant to so many moves adds up to a juggernaut pokemon indeed.
----Arguments to Keep:
Totally reliant on sandstorm to be that devastating, but is still quite dangerous in his own right, but much less so. His very few counters/checks are popular and good pokemon.
----Personal Opinion:
In all honesty, what puts him over the edge for me is rapid spin. All the other bells and whistles make him great, but even they are quite overcomeable. The biggest reason is obviously that the other Weathers, Mach Punch, Skarmory, Gliscor and Bronzong are all very popular and very useful/powerful, which can render Excadril neutered EXCEPT for rapid spin. Rapid Spin on a pokemon which cannot be countered by any ghost and can also do all the other things that he does puts him over the tipping point for me. I vote ban.
--------------------Reunicles
---Arguments for Ban
Arguably the best ability in the game on a Pokemon with great stats, and a great movepool to abuse those stats. In 3 moves (Psychic, Shadow Ball, Focus Blast), not only does it get perfect coverage, there is nothing that isn't 2HKO'd after a single boost, while most things are OHKO'd. Even without a boost, everything barring very specific and overcentralized counters are simply 2HKO'd while a large number of things are still OHKO'd. Removing Shadow Ball removes coverage from Psychics, which can't touch Reuncules in the first place, leaving room for Recover. Counters for one of Reuncules set's will be beat by a different one. The only reliable counters for every Reuncules are way too overcentralized and specific just for him (like Spec. defensive Drapion). And even they can lose a large amount of the time.
---Arguments to Keep:
Once the set is figured out, easier to counter (slightly). Weak to pursuit (beats them anyway usually). Horrendously slow speed just about guarantees it getting hit before moving (unless it uses trick room, and even if it doesn't bulky enough to take most hits).
----Personal Opinion:
You can probably tell from my weak arguments to keep it from being banned how i feel. Its just too good. The only way to kill it is to damage it from direct attacks due to its ability. This causes a number of problems. First and foremost is that whenever Reuniclus feels at all threatened (rarely), it has no penalty for switching in and out, so keeping whatever means you have of counterring Reunicles healthy is already a losing battle. Secondly, hitting it directly is hard in itself because of Trick Room which allows Reunicles to hit you first, usually killing you. Thirdly, even actually damaging it doesn't do too much because of its great bulk. Theres just too much for it to be OU. This is the easiest one for me. I Vote BAN. PLEASE!!
----------------Other points of interest:
----I'd like to examine Thundurus to some degree. Thundurus is dangerous enough as it is. It also should have Mischievous Heart?
---I would NOT like to examine Drizzle. What people fail to realize is that the fact that Drizzle is in fact BALANCING the metagame. If you Ban Drizzle, Sandstorm will become too powerful because now in Gen 5, Sand is an offensive presence as well. Sun and Hail are too inferior for a host of reasons to begin with as "checks" for sand with or without Drizzle. The thing is, if you ban drizzle, you'll have to ban Sand.
-------Recap:
So, to recap I'd like to Keep Latios, and Ban both Deoxys, Excadril, and Reuniclus. I'd like to look at Thundurus, and Stop looking at Drizzle. I tried to be as rational as i could in every scenario.