ok so i'm not going to really bother to read through the entire thread and quote and pick at every single post (yet), so instead i'm just going to offer my thoughts on lando-i and maybe some counters to the typical arguments used.
ban landorus.
so why do i want to ban landorus? i think a lot of it has already been stated in this thread prior in different wording, but i do believe that landorus-i is just as broken in BW as it is in XY. landorus-i is, without a doubt, the best balance breaker in the entire OU metagame. landorus-i is a better breaker than any mega in the game flat out. without any boosts lando-i still retains incredible amounts of power, and it doesn't help that it takes 0 damage from life orb, and all it's attacks are boosted up by sheer force. lando-i is balances worst nightmare pretty much. fast enough to beat the majority of pokemon on balance, bulky enough to survive a few hits, and strong enough to ohko or 2hko anything that comes in it's way. while landorus is not nearly as good vs offense as it is vs balance, it can still destroy offense if it gets the chance to RP, or predicts correctly and nails something with a focus blast, swave, or hp ice (or whatever other coverage move). landorus is no questions asked an amazing pokemon.
a lot of the anti-ban posts here revolve around the same few arguments: landorus has checks AND counters which can fit on a variety of teams / it has a bad speed tier / without team support lando-i can't break it's counters.
landorus-i has about 1 actual counter. remember dpp mixmence? yeah, lando-i is like that. the only pokemon that can consistently beat lando-i and switch into it over and over without much worry is mega latias, who doesn't care much about HP Ice. outside of that i really cannot think of any pokemon that can consistently switch into and beat landorus-i.
onto checks, a lot of the typical lando-i checks really are not that great. you have...
rotom-w - which i think is a really shitty pokemon in general, but aside from my personal hatred of it, rotom-w can't switch into shit unless it is full sdef, and even then it still takes a ton from focus blast / sludge wave. rotom-w typically runs a physically bulky spread in this metagame though, so these attacks are going to do even more. rotom-w can really only come in on earth power, hp ice, and rock slide, and if it is weakened even just a bit, it isn't going to be able to tank more than 1 attack of lando. it gets hit once on a prediction, or gets hit and lando switches out, the ability to check landorus fades away.
252 SpA Life Orb Sheer Force Landorus Focus Blast vs. 248 HP / 0 SpD Rotom-W: 191-226 (63 - 74.5%)
252 SpA Life Orb Sheer Force Landorus Sludge Wave vs. 248 HP / 0 SpD Rotom-W: 153-181 (50.4 - 59.7%)
lati@s - when latias isn't mega, it is a very shaky switch to lando-i. for a pokemon that is so often paired with pursuit, it really is at risk every single time it switches in. latios takes a ton from both sludge wave and hp ice, and if it gets hit with a knock off it is essentially screwed.
252 SpA Life Orb Sheer Force Landorus Sludge Wave vs. 0 HP / 4 SpD Latios: 148-175 (49.4 - 58.5%)
0 Atk Life Orb Landorus Knock Off (97.5 BP) vs. 0 HP / 0 Def Latios: 265-312 (88.6 - 104.3%)
252 SpA Life Orb Landorus Hidden Power Ice vs. 0 HP / 4 SpD Latios: 146-172 (48.8 - 57.5%)
latios is basically forced to roost if it gets hit even just once by HP ice or swave, and it is pretty much dead if it gets smacked by a knock off. latias on the other hand can tank these attacks easier (but not that much easier, only a bit), but is a little easier to pursuit due to her weaker offensive stats. the two most commonly used lando-i checks pretty much, these two, while good initial switches, can have their momentum killed by a simple prediction, or simply be pursuited by a teammate.
tornadus-t: probably the "best" lando check, torn-t can switch into pretty much everything lando-i can throw at it and manage to re generator it off, for the most part. although then again, hp ice and swave both do around 35-41, nullifying regen, especially when compounded with rocks / sand if they are on the field. oh, and did i mention that torn-t gets destroyed by rock slide?
0 Atk Life Orb Sheer Force Landorus Rock Slide vs. 128 HP / 0 Def Tornadus-T: 268-317 (80.9 - 95.7%)
tornadus CAN for the most part consistently switch in, but you're still taking quite a bit from a swave or hp ice if you get hit by it.
zapdos - lol come on. i guess sdef zapdos is an OK check? but don't you kinda lose the merit of being able to beat scizor, talonflame, pinsir, etc consistently by switching to full sdef?
cresselia - are you people being serious here?
chansey - chansey only fits on one team archetype in ORAS, and even though it can tank a focus blast, chansey has always been insanely easy to pressure, especially if sand / hazards are on the field. it also doesn't help chansey that it can potentially be knocked off and lose it's top tier defenses, or that it can take 32-38% from a focus blast from a lando-i.
that is what you got pretty much check / counter wise, which really isn't all that much considering that most of them are shaky at best in what they do.
onto my next point, lando-i does not have a bad speed tier. sure it is not hitting 350+ speed or anything crazy like that, but it is certainly fast enough that it can outrun a decent majority of the metagame and do damage to pretty much every part of it. lando-i doesn't need to be crazy fast to beat the shit out of balance or slower teams, all it really needs is 100 base speed and it is good to go. i guess it can be outsped and killed by a bunch of pokemon, which is probably your point, but the fact of the matter is that most of those pokemon are going to have a very hard time just outright switching into lando-i.
and of course, there is always the argument that "well lando needs TEAM SUPPORT!!!!!!!!!!" yeah, we get it. most of the time landorus is not going to be outright 6-0ing teams from team preview, but neither is stuff like ho-oh or rayquaza. of all the pokemon that need team support to do heavy damage, landorus needs the least. you need to basically pair one thing with it, a pursuiter. you have quite a few options for this as well, ttar, bisharp, weavile, hell even scizor can be used. every single pokemon needs team support to do well, lando is not an exception. but that team support is very minimal and typically will succeed in it's job of eliminating stuff that gives lando-i trouble (latias).
i guess what i'm trying to get at here is that lando-i is completely broken. it restricts team building a lot as well, which really isn't a thing that we need in ORAS at this point in the metagame. you basically are forced into a rigid archetype if you're using balance, one in which you basically must have at least 2 lando checks in order to get by. if landorus is banned, i can guarantee the metagame will be far different than it was prior. teams won't need to be as rigid (they still will not counter everything because it's oras lol), and i'm sure variety in balance / defensively oriented teams will begin to expand. remember how bad BW was when lando-i was in the metagame, and how it improved drastically once it was removed? hopefully the same can be said about xy.
EDIT: quote my post and argue with me you anti-ban bastards