Talonflame
Type: Fire / Flying
Base Stats: 78 / 81 / 71 / 74 / 69 / 126
Ability: Flame Body / Gale Wings
Talonflame is seen as one of the best revenge killers in the metagame, primarily due to its high Speed and excellent ability in Gale Wings. This ability gives priority to its Flying-type moves, allowing it to revenge, sweep, and clean with Brave Bird, which functions as a powerful, priority STAB move. It can also hit hard with Flare Blitz, which prevents it from being walled by Steel-types. Talonflame has two effective boosting moves in Swords Dance and Bulk Up, and it can also create momentum with its fast U-turn, while also having priority Roost to help mitigate the damage it takes from its recoil moves. Because of its high Speed, it has the freedom to run a Choice Band set, which takes advantage of Talonflame's stat spread perfectly. This marks Talonflame as a potent threat, and its ability to fill a multitude of roles only adds to its effectiveness in the metagame.
Bisharp
Type: Dark / Steel
Base Stats: 65 / 125 / 100 / 60 / 70 / 70
Ability: Defiant / Inner Focus / Pressure
With access to Defiant, Swords Dance and powerful STAB moves; Sucker Punch, Knock Off and Pursuit, Bisharp is one of the deadliest sweepers and offensive supporters in the metagame. It has an excellent Attack stat, and its unique typing makes it the only Steel-type that still resists Ghost- and Dark-type moves, while its own Dark-type STAB, Knock Off, is now able to break through other Steel-types. In addition, Knock Off is both powerful, and removes a foes item, threatening offensive and defensive Pokemon alike. Bisharp's ability, Defiant, makes it a perfect switch-in to Defog, doubling its Attack, while also meaning that Sticky Web and Intimidate only benefit it. Its secondary STAB in Iron Head also threatens the new Fairy-types, and it even has Pursuit to trap various Dark-type weak threats. Bisharp applies constant offensive pressure, and is one of the most effective attackers in the Overused environment.
Mega Charizard Y
Type: Fire / Flying
Base Stats: 78 HP / 104 Atk / 78 Def / 159 SpA / 115 SpD / 100 Spe
Ability: Drought (Blaze / Solar Power)
Mega Charizard Y is renowned as one of the best wallbreakers in OU thanks to its extremely high Special Attack, decent Speed, and ability Drought. With the sun Drought brings, Mega Charizard Y can fire off extremely powerful sun-boosted Fire Blasts, which outright slaughter much of the OU tier. It is unique among Fire-types in that it can murder both Heatran and Water-types with its coverage, which includes Focus Blast and sun-enhanced Solar Beam. Thanks to its large Special Defense stat, Mega Charizard Y can take a battering from special attacks, heal up with Roost, and outright demolish their users. Furthermore, because the opponent does not know which Mega Charizard this is when it comes out, he or she is left to guess what to switch in initially, which can be punished. Combine all this with resistances to key types like Fighting, Bug, Fire, and Steel, and you have a frightening offensive Pokemon that given but one free opportunity can do serious harm to any team.
Umbreon
Type: Dark
Base Stats: 95 HP / 65 Atk / 110 Def / 60 SpA / 130 SpD / 65 Spe
Ability: Synchronize / Inner Focus
Umbreon carves out its niche in the metagame through the combination of several factors that distinguish it. Its phenomenal mixed bulk allows it to avoid 2HKO's from powerful attacks, even some non-STAB super effective ones, using its free turns to provide the team with Wish and Heal Bell support that will make efforts to wear down Umbreon's team extremely frustrating. In addition to being a sturdy wall and team supporter, though, Umbreon also maintains a modest offensive presence through its very useful Foul Play that prevents it from being setup bait for physically offensive threats. This deals heavy damage to many physical attackers that wish to break down Umbreon, and in combination with its good defensive typing and recovery, Umbreon is like a bad meal; it hurts and can't be kept down.
Mega Absol
Type: Dark
Base Stats: 65 HP / 150 Atk / 60 Def / 115 SpA / 60 SpD / 115 Spe
Ability: Magic Bounce (Pressure / Super Luck / Justified)
Mega Absol is blessed with huge Attack and Speed stats and an often-overlooked Special Attack stat that allows it to wall break or sweep depending on what is needed. Despite its frailty, its useful ability in Magic Bounce allows it to setup a Swords Dance on a variety of defensive Pokemon. Sucker Punch gives it extremely powerful priority that can be used to revenge kill Psychic- and Ghost-type attackers or sweep offensive teams. Knock Off also gives it a strong, more reliable option that has great utility against almost all Pokemon. Mega Absol's wide movepool allows it to choose its own counters, and if necessary it can even Baton Pass its boosts along to another sweeper, as almost no battler would attempt to phaze Mega Absol. The power, speed, and utility that Mega Absol provides makes it a lethal threat capable of sweeping or disrupting many teams if given the opportunity.
Mega Mawile
Type: Steel/Fairy
Base Stats: 50 HP / 105 Atk / 125 Def / 50 SpA / 95 SpD / 50 Spe
Ability: Huge Power
Sporting the highest attack stat in the game, surpassing even Deoxys-A and Thick Club Marowak, Mega Mawile is a dangerous wallbreaker of frightening power. Its Steel/Fairy typing, the Intimidate ability in its base forme, and its deceptive bulk in Mega forme afford it many opportunities to switch in, set up, and wreak havoc. Its excellent coverage and access to powerful priority in Sucker Punch to work around its glacier-like speed make it even deadlier. Swords Dance doubles its already sky-high attack to absurd levels; the list of things that can stomach a +2 Sucker Punch is quite short. It can alternatively use a Substitute set which, while not as powerful and lacking reliable recovery, protects it from the crippling burn status and frees opportunities to use non-priority attacks from a still extremely high attack stat. Finally, Mawile's movepool is extensive, potential counters can easily be hit harder than they might expect. Because of its sheer might, Mega Mawile has the potential to be a formidable threat to offensive and defensive teams alike.
Skarmory
Type: Steel / Flying
Base Stats: 65 HP / 80 Atk / 140 Def / 40 SpA / 70 SpD / 70 Spe
Ability: Keen Eye / Sturdy / Weak Armor
By virtue of its extremely high Defense stat and great defensive typing, Skarmory is a solid switch-in and counter to many prominent physical attackers. It's one of the few Steel-types that is immune to Ground-type moves and neutral to Fighting-type moves, and carries with it an impressive eight resistances and two immunities that stops many. Access to reliable recovery makes Skarmory one of the most durable physical walls, while Whirlwind prevents it from becoming setup bait. The entry hazards it can lay down punish the special attackers that switch into it, and access to Defog can easily eradicate entry hazards detrimental to its own team. Overall, Skarmory's impressive physical bulk and amazing utility value make it a major defensive threat that must be played around carefully.
Gengar
Type: Ghost / Poison
Base Stats: 60 HP / 65 Atk / 60 Def / 130 SpA / 75 SpD / 110 Spe
Ability: Levitate
Gengar sports two very high stats in Special Attack and Speed, and can certainly use them well with a great STAB and solid coverage options. However, because of the extremely effective non-attacking moves Gengar has access to, it fights very differently than other fast special threats. Gengar's Substitute is notoriously easy to set up, thanks to Gengar's great typing and ability. Disable takes care of the many opponents that rely on a single move to hit Gengar, Taunt shuts down any attempt to indirectly deal with Gengar, and Will-O-Wisp is a nasty surprise to any physical attackers hoping to hit it on its weaker Defense stat. These support options, coupled with the fact that Gengar needs only two attacking moves to hit the entire tier for neutral damage, make Gengar an extremely unconventional but equally deadly threat to teams of all varieties.
Volcarona
Type: Bug / Fire
Base Stats: 85 HP / 60 Atk / 65 Def / 135 SpA / 105 SpD / 100 Spe
Ability: Flame Body / Swarm
Volcarona is a fearsome sweeper if given even one free turn. A huge base 135 Special Attack stat and decent Speed combined with access to one of the best boosting moves in the game in Quiver Dance allows Volcarona to blast through an unprepared team with only one turn of setup. A good typing gives it strong STAB moves and as a virtue of it, Volcarona has several resistances that it can use to set up. In lieu of a fully offensive set, it can also run a bulkier set that sets up with frightening ease on physical and special attackers alike, even those with super effective moves. While there are several threats that can almost always prevent Volcarona from doing its job, if these are removed then Volcarona will usually have a chance to sweep and one must be careful not to give it a chance to do so when facing it.
Kyurem-B
Type: Dragon / Ice
Base Stats: 125 HP / 170 Atk / 100 Def / 120 SpA / 90 SpD / 95 Spe
Ability: Teravolt
Boasting the 4th highest BST in the game, surpassed only by the Mega Mewtwo forms and Arceus Himself, Kyurem-B is almost as dangerous as it seem. An obscene Attack stat and a great Special Attack stat allow it to attack effectively from both sides of the spectrum, and excellent bulk means it is very difficult to take down. Its ability is also helpful, allowing it to bypass many defensive Pokemon's abilities like Thick Fat or Levitate. An ample movepool gives Kyurem-B strong STAB moves, good coverage options, and a variety of sets it can run. Its typing gives it some useful resistances, thus Kyurem-B finds it easy to create and maintain a Substitute, while it can also be an all-out attacker that is relatively effective at stallbreaking.
Cresselia
Type: Psychic
Base Stats: 120 HP / 70 Atk / 120 Def / 75 SpA / 130 SpD / 85 Spe
Ability: Levitate
A defensive juggernaut to the core, Cresselia has no issues taking a plethora of hits from the offensive Pokemon littered around the tier. Cresselia's phenomenal mixed bulk in tandem with its access to recovery and Levitate allow it to take on common threats such as Terrakion, Dragonite, Garchomp, and Keldeo. Aside from its defensive prowess, Cresselia is also a stupendous dual screener. Cresselia's biggest draw as a utility Pokemon, Lunar Dance, provides Cresselia with a means of completely restoring a battered teammate and distinguishes Cresselia from other users of the dual screens strategy. Despite lackluster typing, Cresselia shines as a supporting Pokemon in the metagame and is a defensive threat which every team should be prepared to deal with.
Togekiss
Type: Fairy / Flying
Base Stats: 85 HP / 50 Atk / 95 Def / 120 SpA / 115 SpD / 80 Spe
Ability: Hustle / Serene Grace / Super Luck
With solid bulk, respectable Special Attack, and a useful Fairy/Flying type, Togekiss is a good special wall. Its crucial type advantages against Dragon, Ground, and Fighting enables it to handle dangerous special threats as Latios and Landorus, and even some physical ones as Dragonite and Conkeldurr. Though somewhat held back by a Stealth Rock weakness, it has access to reliable recovery to offset the damage. Its support movepool is expansive, containing gems such as Defog, Thunder Wave, and Heal Bell. Its Serene Grace ability makes it an infamous abuser of the "paraflinch" strategy, in which slowed-down opponents are whittled as successive flinches and full paralysis immobilize them. Overall, Togekiss' durability, utility, versatility, and even disruptive potential makes it a notable defensive threat.
Gyarados
Type: Water / Flying
Base Stats: 95 HP / 125 Atk / 79 Def / 60 SpA / 100 SpD / 81 Spe
Ability: Intimidate / Moxie
Gyarados has many great traits to make it a threatening Dragon Dance user in the metagame. Alongside its great attack stat, Gyarados has two excellent abilities that make it even more dangerous of a sweeper. Intimidate helps it take hits better and Gyarados has several useful resistances and a decent bulk in order to set up on a myriad of Pokemon; these resistances include one to many common priority moves seen in OU, Fire, Fighting, and more. This makes it not uncommon for Gyarados to find the opportunity to set up multiple Dragon Dances without too much of a problem. Moxie can alternatively be useful to prevent opponents from sacking Pokemon agianst Gyarados in an effort to bring in a would be counter freely. Its Water STAB gets good coverage on its own and a STAB Bounce allows it to take on Grass-types that usually threaten Water-types, and it has many coverage moves, such as Stone Edge, Ice Fang, and Earthquake, to deal with other Pokemon as well, making it tough to wall.
Mega Gyarados
Type: Water / Dark
Base Stats: 95 HP / 155 Atk / 109 Def / 70 SpA / 130 SpD / 81 Spe
Ability: Mold Breaker (Intimidate / Moxie)
Just like Gyarados, Mega Gyarados is a threatening Dragon Dance sweeper. 155 base Attack is exceedingly high, with it, its good STAB and myriad of coverage moves hit damn hard. With Mold Breaker it has the potential to get past a wide variety of Pokemon that it otherwise could not such as Rotom-W, Quagsire, and Mega Venusaur. Mega Gyarados' type change is as useful as it is unique, having the luxury of setting up on Pokemon that either Water/Flying or Water/Dark allows. The additional bulk, which sits at a great 95/109/130, is also helpful, and unlike base Gyarados it doesn't have to deal with any 4x weaknesses or a Stealth Rock weakness, meaning it is difficult to outright KO. All these traits allow Mega Gyarados to simultaneously act as a threatening sweeper and wallbreaker.
Mega Scizor
Type: Bug / Steel
Base Stats: 70 HP / 150 Atk / 140 Def / 65 SpA / 100 SpD / 75 Spe
Ability: Technician
Thanks to Technician and an extremely high base 150 Attack stat, Mega Scizor finds itself in possession of one of the strongest priority moves in the game in the form of Bullet Punch, allowing it to revenge kill many weakened threats. Furthermore, Swords Dance lets Mega Scizor easily sweep late-game once its counters have been sufficiently weakened, and Scizor can easily use its outstanding bulk, Roost, and nice typing to set up two or even 3 boosts. Access to STAB U-turn lets Mega Scizor exit the field while dealing significant damage to many of the defensive threats that may attempt to check it. With a movepool consisting of many other options such as Pursuit, Knock Off, and more, Mega Scizor has a way to threaten or cripple just about every other Pokemon in the tier.
Shuckle
Type: Bug / Rock
Base Stats: 20 HP / 10 Atk / 230 Def / 10 SpA / 230 SpD / 5 Spe
Ability: Sturdy / Gluttony / Contrary
Shuckle's hilarious stats notwithstanding it indeed has a notable niche in OU. Impressive overall defenses make Shuckle the most resilient and reliable user of the powerful Sticky Web. Access to Encore prevents opponents from taking advantage of it freely, and it can be used to deter Defog and Rapid Spin users from removing Shuckle's hazards, or punish them if they do. Sturdy affords a Mental Herb with little regrets letting Shuckle act as a pretty effective lead, and Stealth Rock is always a nice touch. Sum these traits, and Shuckle is something that can threaten teams with its utility.
Mega Ampharos
Type: Electric / Dragon
Stats: 90 HP / 95 Atk / 105 Def / 165 SpA / 110 SpD / 45 Spe
Ability: Mold Breaker
When looking at Mega Ampharos, the first things that stands out are its glorious locks, and its unique Electric/Dragon typing, shared only by the Uber titan Zekrom. When looking at his stats, the first two things that immediately stand out are its colossal 165 base special attack, the second highest in OU, and its atrocious base 45 speed. However one thing to not overlook is its base 90 / 105 / 110 base defenses, which, when invested, make Mega Ampharos ridiculously tanky, and as a result, one of Ampharos' best sets is a Volt Switch set, as it is capable of taking virtually any hit at full health and safely switching into a deadly sweeper in waiting. It is in this such role that its bad speed is actually a blessing, as this allows it to function as a fantastic pivot switch, arguably the most optimized pivot switch in the game. If utilized in an even more offensive manner, its Speed can be patched up quickly with Agility, turning Mega Ampharos into a deadly sweeper.