Heatran @ Air Balloon
Ability: Flash Fire
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature
IVs: 2 Atk / 30 Def
- Fire Blast
- Earth Power
- Ancient Power
- Hidden Power [Ice]
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 236 SDef / 20 Spd
Calm Nature
IVs: 0 Atk
- Giga Drain
- Stealth Rock
- Psychic
- Recover
Gyarados @ Leftovers
Ability: Intimidate
EVs: 248 HP / 252 Def / 8 SDef
Impish Nature
- Rest
- Sleep Talk
- Waterfall
- Roar
Genesect @ Choice Scarf
Ability: Download
EVs: 252 Spd / 252 SAtk / 4 Atk
Hasty Nature
- Flamethrower
- Ice Beam
- Thunderbolt
- U-turn
Kangaskhan (F) @ Kangaskhanite
Ability: Scrappy
EVs: 252 Atk / 4 HP / 252 Spd
Jolly Nature
- Return
- Power-Up Punch
- Sucker Punch
- Earthquake
Sylveon @ Leftovers
Ability: Cute Charm
EVs: 252 HP / 252 Def / 4 SDef
Bold Nature
IVs: 0 Atk
- Wish
- Protect
- Heal Bell
- Draining Kiss
Ability: Flash Fire
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature
IVs: 2 Atk / 30 Def
- Fire Blast
- Earth Power
- Ancient Power
- Hidden Power [Ice]
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 236 SDef / 20 Spd
Calm Nature
IVs: 0 Atk
- Giga Drain
- Stealth Rock
- Psychic
- Recover
Gyarados @ Leftovers
Ability: Intimidate
EVs: 248 HP / 252 Def / 8 SDef
Impish Nature
- Rest
- Sleep Talk
- Waterfall
- Roar
Genesect @ Choice Scarf
Ability: Download
EVs: 252 Spd / 252 SAtk / 4 Atk
Hasty Nature
- Flamethrower
- Ice Beam
- Thunderbolt
- U-turn
Kangaskhan (F) @ Kangaskhanite
Ability: Scrappy
EVs: 252 Atk / 4 HP / 252 Spd
Jolly Nature
- Return
- Power-Up Punch
- Sucker Punch
- Earthquake
Sylveon @ Leftovers
Ability: Cute Charm
EVs: 252 HP / 252 Def / 4 SDef
Bold Nature
IVs: 0 Atk
- Wish
- Protect
- Heal Bell
- Draining Kiss
One of the more potent defensive cores in generations past, Celetran, comes to XY a bit battered but not broken. With the Steel nerf, Heatran can no longer come in on Dark or Ghost type attacks with impunity, but with some support, the core remains.
Heatran @ Air Balloon
Ability: Flash Fire
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature
IVs: 2 Atk / 30 Def
- Fire Blast
- Earth Power
- Ancient Power
- Hidden Power [Ice]
The lava slug is poised to leave its mark in OU once again. I have opted for an offensive Air Balloon set. Fire Blast still hurts despite the power drop, leaving dents in anything that doesn't resist it. Earth Power and HP Ice have been common on offensive Heatran in the past, and they remain that way. Even though HP got nerfed as well, it still covers Dragons easily, doing about 84-98% to Garchomp, for example. Ancient Power is an odd but effective choice, hitting Rotom-W switch ins and allowing it to actually kill Talonflame instead of just walling it. (And in case you were wondering, no, sadly, I have not gotten the hax from it yet.)
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 236 SDef / 20 Spd
Calm Nature
IVs: 0 Atk
- Giga Drain
- Stealth Rock
- Psychic
- Recover
Complementing Heatran nicely is Celebi. A specially defensive set is well suited for OU's resident forest pixie. Giga Drain and Recover make it hard to kill with power alone, and Natural Cure circumvents status. Psychic gives some coverage and can surprise players who switch out their Rotom-W, provided the switch in isn't Dark type. Stealth Rock allows Celebi's teammates to get easier O- or 2HKO's.
Gyarados @ Leftovers
Ability: Intimidate
EVs: 248 HP / 252 Def / 8 SDef
Impish Nature
- Rest
- Sleep Talk
- Waterfall
- Roar
One of the things Heatran and Celebi struggle with is their ability to take physical hits. Enter Gyarados. If you read the "Silly Things You've Seen on the OU Ladder" thread, you may have noticed me giving this set some flak. Well, that was before I tried it. Lesson learned: don't judge a book by its cover. Gyarados makes a great counter to EQ users or Talonflame, should I wish to preserve Heatran's balloon. RestTalk and Intimidate allow Gyarados to overcome its SR weakness. Waterfall is the most consistent attack it gets, and Roar allows it a way to check threats such as Aegislash, Lucario, and Kangaskhan.
Genesect @ Choice Scarf
Ability: Download
EVs: 252 Spd / 252 SAtk / 4 Atk
Hasty Nature
- Flamethrower
- Ice Beam
- Thunderbolt
- U-turn
The paleo bug is back in OU (for now) with a vengeance. This is probably the best set it can run, and with good reason. Thanks to its scarf, Genesect is a great scout and revenge killer. Of course, let's not forget its power, which is more than enough to get some sweeps of its own, especially with Download. It can also weaken stuff it can't kill, making a sweep easier.
Kangaskhan (F) @ Kangaskhanite
Ability: Scrappy
EVs: 252 Atk / 4 HP / 252 Spd
Jolly Nature
- Return
- Power-Up Punch
- Sucker Punch
- Earthquake
On the topic of sweeping, here's what does it the most. Even without the PuP boost, Parental Bond makes Mega Kangaskhan so dangerous. No Sash or Substitute user is safe from taking two hits like this, able to destroy nearly anything that doesn't resist the move she has chosen. She's also one of the few things that can reliably beat Mega Gengar, although not with complete impunity.
Sylveon @ Leftovers
Ability: Cute Charm
EVs: 252 HP / 252 Def / 4 SDef
Bold Nature
IVs: 0 Atk
- Wish
- Protect
- Heal Bell
- Draining Kiss
Finally is the newest member of the Eevee family, Sylveon. Due to its EV spread, it can take physical and special hits fairly evenly. Sylveon's main job on this team is as a cleric, utilizing Heal Bell and Wish quite nicely. Draining Kiss isn't that strong, but it gives some solid healing in case Sylveon gets taunted and can overcome choiced opponents in the lategame, especially if they're weak to it.
Hazards: Thanks to healing, most hazards aren't terribly difficult to deal with. Sticky Web, however, can be a pain for Kangaskhan and, to an extent, Genesect, but their power (and Sucker Punch in Kanga's case) can often overcome it.
VoltTurn: For some reason, I've seen a lot of this while laddering (I'm at 2016 as of the OP), especially with Rotom-W. But with prediction and help from SR, I have beaten most of the VoltTurn teams I've seen, although not exactly quickly.
Aegislash: I just need to stop it from boosting too much, as its power can go crazy quick. I really can't counter it very well, but I can check it.
Greninja: Due to its versatility, it depends on what I have out. Celebi and Heatran cover each other fairly well, as always. Gyarados can come in on a Water attack, Sylveon can take Dark Pulse, and Genesect can take Ice Beam. Of course, prediction comes into play as well.
VoltTurn: For some reason, I've seen a lot of this while laddering (I'm at 2016 as of the OP), especially with Rotom-W. But with prediction and help from SR, I have beaten most of the VoltTurn teams I've seen, although not exactly quickly.
Aegislash: I just need to stop it from boosting too much, as its power can go crazy quick. I really can't counter it very well, but I can check it.
Greninja: Due to its versatility, it depends on what I have out. Celebi and Heatran cover each other fairly well, as always. Gyarados can come in on a Water attack, Sylveon can take Dark Pulse, and Genesect can take Ice Beam. Of course, prediction comes into play as well.
I've done well with this team, having gotten over 2000 ACRE, but I am still open to constructive criticism.