The last part of this is false. Breloom's sets all have that awful Grass/Fighting coverage in common, so they actually very frequently share the same checks and counters (removing Gliscor and Gengar for Technician sets since they don't like taking Bullet Seeds).
CB Breloom, all out attacker Breloom, and Leech Seed Breloom all can defeat common checks and counters to other sets. Gengar, Xatu, Gliscor (which is a shitty check anyway), Torn-T, Lati@s, and Dnite, all common switch-ins to Breloom after Sleep Clause has been activated, can be defeated by the appropriate set, which leaves only Celebi as a true counter to Breloom.
"Sweeping better" is all that matters, really. Let's look at Breloom's sets: Physical attacker with Life Orb/Choice Band, Swords Dance, Choice Scarf, and Sub sets with Poison Heal. And once again, all of these sets have many checks/counters in common, and it's not like Scarf Breloom is common at all. Often times the Pokemon that actually gets put to sleep is that Pokemon that won't end up doing much for the rest of the battle anyway (I switch in the least useful member of my team into Spore a lot, why wouldn't I?) As for Sporing something.... Breloom's slow and frail, man. Not really a good combo. Best you can do is force out something weak to Mach Punch or choice-locked, but in the former case they may just end up predicting you to go for Spore and simply kill you.
Scarf Breloom is almost never seen so i won't count for it. But i really fail to get how you can say that sweeping better is all that matters when out of all the sets you listed only the SD set aims to sweep. And no they don't have many checks in common. In fact this is the point of using CB in the first place, to lure common switch-ins to Breloom and destroy them. As you said the least valuable member will be put to sleep, but this is still a loss and counts as losing a Pokemon. As for Breloom being slow and frail, i agree, but it still can get plenty set-up opportunities due to all its threatening traits. It can either Spore a slower mon, force out a faster mon with Mach Punch, or take a hit from a faster mon and then use Spore.
This post has a few things wrong with it. Firstly, Breloom is pretty much only a sweeper, yes, you can have that gay Spore / Leech Seed / Protect / Drain Punch set (or whateverit is), but by and large its a sweeper. Secondly, as pointed out Breloom doesn't really "get around" its counters (outside of Spore), since its move are pretty much in stone (grass / fighting / Spore / SD or another fighting move) as many of its sets share the same base counters or checks. Its also somewhat tricky for Breloom to set up, you can run bulk, but then you lose out on priority wars, and if you run speed then boosted water attacks do a ton, which, added with Life Orb means that you are not hanging around for long. Compare this with Terrakion, which also has a fair few number of weaknesses, but under sandstorm it can take a large number of special attacks, without sandstorm it still has excellent bulk which let it set up a sub, SD, or Rock Polish boost, making it truly tough to handle. I think Breloom is a top tier pokemon, easily on of the better pokemon in A rank, but I hardly see it as a "potential" suspect at this stage of the metagame, and yea, I think it belongs in A Tier.
Breloom is not pretty much only a sweeper. You are talking about SD Breloom, which is not its only set. CB or all out attacker Breloom, SubPunch and finally Leech Seed Breloom are not sweepers, they are wallbreakers and annoyers. Just because SD Breloom is the most popular set doesn't mean i should only talk about it.
Breloom doesn't get around its counters? Oh really? Then why can CB Breloom beat Xatu, Dragonite, Latias, and Sleep Talk Torn-T, pokes that usually counter it (some of them after Sleep Clause)? Why does the Leech Seed set easily build residual damage on would be counters, beating them in the long run, or allowing to your other Pokemon free switches? Or why the whole game turns around when you send your death fodder in Breloom, in order to bring in your revenge kiler safely after it dies, when what you were expecting to be an SD Breloom turns out to be a SubPunch set, meanin the Breloom gets a sub on the switch, kills the death fodder and then proceeds to fuck you up?
Finally you are right that Breloom's flaw lies to his low bulk and speed, which sometimes makes it tricky to bring in, but still i believe that he finds plenty set-up opportunities. Be it against a slower poke that he can Spore and then set-up, against a faster poke that he can force out with Mach Punch, or against a faster poke that cannot OHKO it, Breloom will find the set-up opportunity it needs to get started. And once it gets started it will be very dangerous if played right. Simply the fact that against offensive teams Breloom can cripple pretty much two Pokemon guaranteed makes it really good (one with Spore and the second with Fight Gem +2 Mach Punch which almost kills even frail fighting resists that offensive teams carry). Yeah full counters exist, Xatu and Celebi mainly, but let's not forget that Breloom is half the reason that Xatu is seeing the light of OU, and the other half reason is a potential suspect, Deo-D.
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People should really use Hydreigon more, it is disturbing how many here don't have a clue about it. Some say that Latios is a better wallbreaker, some say that Latios is stronger, and some others that Superpower doesn't really help Hydreigon do anything else except from beating Ttar. Hydreigon is a far better wallbreaker than Latios, because it can 2HKO the whole tier, with zero exceptions. Yeah even Chansey if you are smart and you EV it right. Hydreigon is stronger than Latios in practice because it can afford to use a Modest nature while Latios can't. If you use a Modest nature on Latios then you are doing something wrong, which means that Modest Latios is non existent in practice. Finally Superpower is super useful and allows Hydreigon to deal with Ttar, Blissey, Chansey, and Heatran.
Lol wow, you're right, DrNeoCortex :o Stoutland should definitely join the ranks of Venusaur - double speed in Sand is almost unfair! HippoLand has been around for quite some time now, with users such as
Gamestar and
The Great Mighty Doom popularizing it with their respective RMTs.
Actually Stoutland has been discussed before, and the general consensus was that while it is good, it is somewhat outclassed by Scarf Landorus as a revenge killer for Sand teams, which is the reason why he deserves to be in C Rank. Before anyone jumps in, i said somewhat, not completely, which means that usually Landorus will be the best choice, but Stoutland has its uses as well.