Eh, I might as well put some of my reasoning down.
First off I'm going to say right away I know I'm not the best battler around and my hands-on experience with X & Y is limited. I only have around 50 OU battles logged and I never got above 1500 (though I did win around 80% of my battles. The fact I never got over has more to do with the fact I don't take the time to ladder often enough). However, I've read enough on this topic and in other places to get an idea of how these Pokemon function in practice (since I've heard about it from those who've seen it). One thing I am very good at is analyzing information and forming valid, logical conclusions from said analysis. So that's what I'm going to do here.
M-Lucario: I think it's pretty clear by this point that M-Lucario is going to be banned. Reading through the topic it's very clear to me that the vast majority of the people who are arguing against a ban are very unlikely to make reqs. I don't think this is a coincidence; anyone with a lot of exposure to serious competitive Pokemon can tell that M-Lucario is broken. It's not just the fact that it has very few counters and checks, nor is it just that it's faster than almost everything in OU (There are literally 4 OU Pokemon that outspeed it), nor is it the fact that it has Priority to take out those few things that do outspeed it, nor is it the fact that it can run two sets that have completely different counters. It's all these things put together. Not only is M-Lucario able to both sweep and wallbreak in the same set, it's able to do it at the same time with the same set-up! On top of that it can even revenge kill with it's priority sometimes. Because of these things you almost always lose a Pokemon when facing M-Lucario, or if you don't you typically end up with one or more Pokemon so crippled they almost might as well be fainted. M-Lucario isn't the only Pokemon that can do this, true, but he's one of the only who can do this and still threaten to sweep you if you DON'T sacrifice a Pokemon or two to it. Other so called "uncounterable" Pokemon like Salamence and Hydreigon had the issue that once they broke down a wall they couldn't stay in due to stat drops, or they could be easily and reliable picked off due to being locked into Outrage. Others, like Terrakion, are much more reliant on heavy prediction and were thereby much less reliable. M-Lucario has no such limits. If you don't stop it, it WILL sweep you. You HAVE to risk sacrificing Pokemon to it or you lose. People on the anti-ban side say that it's not so threatening if you don't let it set up, but they don't seem to realize that not letting it set up usually means whatever Pokemon you're standing your ground against it with is going to get KO'd or crippled in the process. A M-Lucario player isn't going to bring it in against a Pokemon that can OHKO it after all, they're going to bring it in against something it forces out.
Despite what people argue, revenge killing M-Lucario is very difficulty and limited to a few Pokemon (many of whom are easily exploited if M-Lucario simply decides to switch out). It has 3 types of 80 BP priority after all, and just enough bulk and the right typing to be able to take at least one hit from most things that can tank one of its hits. And that bit in the parenthesis is very important to remember; M-Lucario has no reason to stay in if it decides it might die, nor is it likely to be trapped in such a situation (unlike stuff that uses Outrage or is Pursuit weak, for example). M-Lucario is virtually immune to SR and IS immune to Toxic Spikes, and Spike stacking is almost dead thanks to defog. Add in Lucario's numerous resistances and it has lots of opportunities to switch back in after it's been forced out. Because of this, revenge killers very frequently only delay the inevitable. Worse, Scarfers and some priority users can be easily used as set-up fodder by other members of M-Lucario's team (Genesect locked into Flamethrower can be set up fodder for Garchomp, for example). This is true to an extent for every offensive Pokemon, but it's worse with M-Lucario because the list of things that actually can revenge kill it is so small that it's easy for a savvy teambuilder to include Pokemon that can take advantage of the more common ones. Then there's the fact that, thanks to it's priority, if these revenge killers are weakened before Lucario begins its sweep it can often just push them aside. It needs much less for this to happen than many other sweepers, thanks to Adaptability giving it so much power.
So what ends up happening is people have to devote multiple checks just to keep Lucario from sweeping them, severely limiting their teambuilding. While it does have one or two semi-reliable counters in Pokemon like Zapdos, these Pokemon don't fit well on many teams, meaning including them makes them a liability against teams that don't have M-Lucario. This, btw, is why you don't see really obscure stuff like AV Azumaril very often; it's not worth cutting your effectiveness against every other team when you can check M-Lucario using multiple viable Pokemon... but it's still a problem because you're forced to include several Pokemon from the list that do check it. It means some Pokemon don't see nearly as much usage as they would purely because they don't work well with Pokemon that check M-Lucario. Over-centralization isn't when people start all putting the same counter on their teams (well, it's not ONLY that), it's when teambuilding becomes severely restricted in any manner because you need to handle just one Pokemon.
So in summary, M-Lucario is definitely broken. It's so powerful that it simply being on the other team gives you a disadvantage unless you prepare for it so much that your team becomes severely disadvantaged against teams that don't include it. It's not only powerful, but difficult to actually remove it from the match. Even if you play 100% correctly it's still likely to cause irreparable damage to your team, and playing 100% correctly comes down to luck because M-Lucario is also unpredictable with its multiple sets and coverage/priority options. You might be able to win against it, but doing so reliably is impossible against an opponent with a similar level of skill to you.
I'm not going to list a bunch of calculations and the like since that's already been done. I'm basing these arguments mostly off what I've seen argued on this thread, with a bit of personal experience as a supplement. If you need confirmation for the points I've made, just read the rest of the thread and you'll see all the empirical information you need.
I'll go into the other suspects in separate posts, seeing as this has turned out a lot longer than I expected. Better to break it up a little I think. Next up: Genesect.
First off I'm going to say right away I know I'm not the best battler around and my hands-on experience with X & Y is limited. I only have around 50 OU battles logged and I never got above 1500 (though I did win around 80% of my battles. The fact I never got over has more to do with the fact I don't take the time to ladder often enough). However, I've read enough on this topic and in other places to get an idea of how these Pokemon function in practice (since I've heard about it from those who've seen it). One thing I am very good at is analyzing information and forming valid, logical conclusions from said analysis. So that's what I'm going to do here.
M-Lucario: I think it's pretty clear by this point that M-Lucario is going to be banned. Reading through the topic it's very clear to me that the vast majority of the people who are arguing against a ban are very unlikely to make reqs. I don't think this is a coincidence; anyone with a lot of exposure to serious competitive Pokemon can tell that M-Lucario is broken. It's not just the fact that it has very few counters and checks, nor is it just that it's faster than almost everything in OU (There are literally 4 OU Pokemon that outspeed it), nor is it the fact that it has Priority to take out those few things that do outspeed it, nor is it the fact that it can run two sets that have completely different counters. It's all these things put together. Not only is M-Lucario able to both sweep and wallbreak in the same set, it's able to do it at the same time with the same set-up! On top of that it can even revenge kill with it's priority sometimes. Because of these things you almost always lose a Pokemon when facing M-Lucario, or if you don't you typically end up with one or more Pokemon so crippled they almost might as well be fainted. M-Lucario isn't the only Pokemon that can do this, true, but he's one of the only who can do this and still threaten to sweep you if you DON'T sacrifice a Pokemon or two to it. Other so called "uncounterable" Pokemon like Salamence and Hydreigon had the issue that once they broke down a wall they couldn't stay in due to stat drops, or they could be easily and reliable picked off due to being locked into Outrage. Others, like Terrakion, are much more reliant on heavy prediction and were thereby much less reliable. M-Lucario has no such limits. If you don't stop it, it WILL sweep you. You HAVE to risk sacrificing Pokemon to it or you lose. People on the anti-ban side say that it's not so threatening if you don't let it set up, but they don't seem to realize that not letting it set up usually means whatever Pokemon you're standing your ground against it with is going to get KO'd or crippled in the process. A M-Lucario player isn't going to bring it in against a Pokemon that can OHKO it after all, they're going to bring it in against something it forces out.
Despite what people argue, revenge killing M-Lucario is very difficulty and limited to a few Pokemon (many of whom are easily exploited if M-Lucario simply decides to switch out). It has 3 types of 80 BP priority after all, and just enough bulk and the right typing to be able to take at least one hit from most things that can tank one of its hits. And that bit in the parenthesis is very important to remember; M-Lucario has no reason to stay in if it decides it might die, nor is it likely to be trapped in such a situation (unlike stuff that uses Outrage or is Pursuit weak, for example). M-Lucario is virtually immune to SR and IS immune to Toxic Spikes, and Spike stacking is almost dead thanks to defog. Add in Lucario's numerous resistances and it has lots of opportunities to switch back in after it's been forced out. Because of this, revenge killers very frequently only delay the inevitable. Worse, Scarfers and some priority users can be easily used as set-up fodder by other members of M-Lucario's team (Genesect locked into Flamethrower can be set up fodder for Garchomp, for example). This is true to an extent for every offensive Pokemon, but it's worse with M-Lucario because the list of things that actually can revenge kill it is so small that it's easy for a savvy teambuilder to include Pokemon that can take advantage of the more common ones. Then there's the fact that, thanks to it's priority, if these revenge killers are weakened before Lucario begins its sweep it can often just push them aside. It needs much less for this to happen than many other sweepers, thanks to Adaptability giving it so much power.
So what ends up happening is people have to devote multiple checks just to keep Lucario from sweeping them, severely limiting their teambuilding. While it does have one or two semi-reliable counters in Pokemon like Zapdos, these Pokemon don't fit well on many teams, meaning including them makes them a liability against teams that don't have M-Lucario. This, btw, is why you don't see really obscure stuff like AV Azumaril very often; it's not worth cutting your effectiveness against every other team when you can check M-Lucario using multiple viable Pokemon... but it's still a problem because you're forced to include several Pokemon from the list that do check it. It means some Pokemon don't see nearly as much usage as they would purely because they don't work well with Pokemon that check M-Lucario. Over-centralization isn't when people start all putting the same counter on their teams (well, it's not ONLY that), it's when teambuilding becomes severely restricted in any manner because you need to handle just one Pokemon.
So in summary, M-Lucario is definitely broken. It's so powerful that it simply being on the other team gives you a disadvantage unless you prepare for it so much that your team becomes severely disadvantaged against teams that don't include it. It's not only powerful, but difficult to actually remove it from the match. Even if you play 100% correctly it's still likely to cause irreparable damage to your team, and playing 100% correctly comes down to luck because M-Lucario is also unpredictable with its multiple sets and coverage/priority options. You might be able to win against it, but doing so reliably is impossible against an opponent with a similar level of skill to you.
I'm not going to list a bunch of calculations and the like since that's already been done. I'm basing these arguments mostly off what I've seen argued on this thread, with a bit of personal experience as a supplement. If you need confirmation for the points I've made, just read the rest of the thread and you'll see all the empirical information you need.
I'll go into the other suspects in separate posts, seeing as this has turned out a lot longer than I expected. Better to break it up a little I think. Next up: Genesect.
