A few hours ago I made a post on this thread expressing my opinions on Chloe's thoughts in a very simple way saying that I was gonna give further elaboration later, but 1. I was too lazy to actually do that and 2. Chloe later removed my post (I could see why since it really wasn't adding much to the conversation). I am here and now I have time to sit down and write a serious post on this matter, so here are my detailed thoughts.
I want to quickban Pidgeotite.
I wholeheartedly agree with this decision. All of the time, broken stuff is fun to use on your side, while your opponent has to suffer, and vice versa. Likewise, I had a lot of fun using Pidgeotite Deoxys-Speed and Gengar (as well as Xurkitree a few times), but in Round 1 of Mix and Mega Open, I lost to a person using a Webs Xurkitree team for two of the three games. (Not sure if it actually had webs) I was trying to run stall of one of them, the other was nothing special with no Diancite Naganadel or strong -atespeed. My third game I used a Diancite Naganadel and that was literally the only method I could circumvent being put to sleep and 6-0ed by Xurkitree. The only two ways to beat Pidgeotite users are either strong priority (where Aerilate is resisted by Xurkitree and Pixilate is resisted by Gengar), or things that outspeed them which, while there is a handful (like Metagrossite Kartana, Diancite Naganadel/Tapu Lele and previously Pidgeotite Deoxys-Speed, but beating broken with broken doesn't seem to be too good of an option), it can sweep a lot more slower mons (like Groudon-Primal) or status most of them using either Hypnosis or Zap Cannon. The only real method to not get statused by these two Pidgeotite users is to run a Magic Bounce stone + immunity to paralysis like using Sablenite Zapdos or Sablenite Hippowdon which are subpar compared to their actual sets. This may sound like a joke, but Mix and Mega is a skill-based metagame; most Pokemon like Sablenite Magearna or Venusaurite Hippowdon require skill to use in pivoting and predicting switches, etc. However Pidgeotite Xurkitree is a mon that requires little skill to use, like you can just Tail Glow, Hypnosis when the situation calls for it, add that to a 100% accuracy strong STAB and Grass Knot for coverage against things like Hippowdon and Groudon-Primal, and you've got a Pokemon that can easily 6-0 without needing to give regards to checks, counters and what not. And teams that basically lack -atespeed and/or extremely fast revenge sweepers can and will be swept by it. Stall teams basically mandate the use of Ditto; As such, we can classify Xurkitree, and Pidgeotite in general as overcentralizing. I personally hate it, and I'm sure the majority of the skilled Mix and Mega players will agree with this decision as well.
I want to unban Shaymin-Sky.
I fully agree with this thought. Shaymin-Sky was never too broken without Pidgeotite; same goes for Darkrai. When Pidgeotite gets banned, both could be viably reintroduced into the tier with their sets being mainly Absolite or Diancite or maybe even some niche Lucarionite set. Deoxys-Speed is another thing though. Gyaradosite allows it to become a very good hazard setter, but I find that much less detrimental to the tier than a strong and fast Special Attacker with viable boosting options, due to hazards being able to be removed by Defog/Rapid Spin. I personally don't find it too troubling, and as such I find it absolutely fine to reintroduce Shaymin-Sky, Darkrai and Deoxys-Speed into the tier once Pidgeotite has been banned.
I want to be more proactive with Uber Pokémon bans.
That is absolutely necessary. Again and again has Pokemon banned from OU proven to be too much for the tier, like with the case of Pheromosa and Marshadow. Another prime example is with my following response to the next point, being Naganadel.
I want to quickban Naganadel.
Naganadel has absolutely no reason to stay in the tier, other than being a Pokemon being able to revenge kill Pidgeotite Xurkitree, even with -1 Speed coming from Webs. Once Pidgeotite goes I really don't see any need in any fast revenge killers with over 170 base Speed due to Webs Xurkitree no longer being a thing. Other than being a fast Revenge Killer, it can also hit hard on just about anything with its few sets, including but not limited to: Zygarde, Magearna, Groudon-Primal, etc. It also gets a viable boosting option in Nasty Plot, which means that it can set up on stuff that it does not OHKO, like Blissey. It was fun to use for a while, but now it's just becoming stale, and like with the Pidgeotite users, it can only be viably defeated by priority or faster revenge killers, which since the removal of Deoxys-Speed no longer exists. So in short just remove Naganadel, please. It can literally kill anything and everything, and really, it restricts teambuilding choices greatly to disallow for some versatile teams.
I want to suspect test Blissey, if metagame trends follow as expected.
I have absolutely no problem with that. Blissey is really tanky and even when there are some Special attackers and most Physical attackers that can beat it, it still poses a problem against most teams, especially with few being able to status it. Its passivity is made up for in Seismic Toss, which deals great damage to things with low HP like Toxapex.
tl;dr qb pidge, free skymin + darkrai + deos, ban everything that gets banned from ou, qb naga, suspect bliss