Counter that Pokémon

Seismitoad (F) @ Leftovers
Trait: Water Absorb
EVs: 252 HP / 252 SAtk / 4 Def
Modest Nature
- Protect
- Aqua Ring
- Earth Power
- Scald

Could withstand all of Metagross' attacks, then take it down with a couple of Earth Powers.

Shaymin @ Leftovers
Trait: Natural Cure
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature (+Spd, -Atk)
- Leech Seed
- Seed Flare
- Psychic
- Substitute

Resists both Scald and Earth Power and OHKOs with Seed Flare.

-Flareon w/Leftovers
Nature: Adamant
Ability: Guts
EVs: 252 Attack, 252 Speed, 4 HP
Moves: Flare Blitz, Flame Charge, Facade, Superpower

252 SpA Shaymin Seed Flare vs. 4 HP / 0 SpD Flareon: 75-89 (27.5 - 32.7%) -- 71% chance to 4HKO after Leftovers recovery
252 SpA Shaymin Psychic vs. 4 HP / 0 SpD Flareon: 76-90 (27.9 - 33%) -- 85.2% chance to 4HKO after Leftovers recovery

Shaymin can only 4HKO, while Flame Charge is enough to break a Sub, and then make Flareon outspeed Shaymin. Flare Blitz OHKOs (duh).

Marshtomp @ Eviolite
Ability: Torrent
Nature: Adamant
EVs: 252 Def / 252 HP / 4 Atk
- Earthquake
- Waterfall
- Double-Edge
- Brick Break

Walls Flareon, then makes it faint instantly with only just one Earthquake.

4+ Atk Marshtomp Earthquake vs. 4 HP / 0 Def Flareon: 314-372 (115.4 - 136.7%) -- guaranteed OHKO

252 Atk Flareon Flare Blitz vs. 252 HP / 252 Def Eviolite Marshtomp: 65-77 (18.8 - 22.3%) -- possible 5HKO
252 Atk Flareon Facade vs. 252 HP / 252 Def Eviolite Marshtomp: 51-60 (14.8 - 17.4%) -- possible 6HKO
252 Atk Flareon Superpower vs. 252 HP / 252 Def Eviolite Marshtomp: 87-103 (25.2 - 29.9%) -- guaranteed 4HKO
252 Atk Flareon Flame Charge vs. 252 HP / 252 Def Eviolite Marshtomp: 27-33 (7.8 - 9.5%) -- possibly the worst move ever

I've been waiting for this:

Mega Pinsir:

-Swords Dance
-Return
-Earthquake
-Quick Attack
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Pinsirite
Ability: Hyper Cutter

Mega Pinsir is only 4HKOed at best by Marshtomp's Waterfall and Double-Edge; it's also immune to Earthquake and takes a pittance from Brick Break. Even unboosted, Aerilate Return does a lot to Marshtomp and it's an OHKO when Mega Pinsir is at +2 Attack.

And just saying, but running Adamant with barely any Attack EVs at all is a waste.

Aggron @ Aggronite
Trait: Filter
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature

- Heavy Slam / Iron Head
- Earthquake
- Rock Slide
- Power-Up Punch

Again, I use Rock Slide > Stone Edge because Mega Aggron is a very defensive pokemon and it wouldn't appreciate a miss. Earthquake can deal 30% at most, while Rock Slide = bye bye Mega Pinsir.

Politoed (M) @ Leftovers
Trait: Drizzle
EVs: 252 HP / 4 SAtk / 252 Def
Bold Nature
- Scald
- Hypnosis
- Ice Beam
- Protect

Could stand any attacks that Aggron tries to use. Thanks to rain, it KOs Aggron with about three Scalds.

4 SpA Politoed Scald vs. 252 HP / 4 SpD Mega Aggron in Rain: 144-171 (41.8 - 49.7%) -- guaranteed 3HKO

252+ Atk Mega Aggron Earthquake vs. 252 HP / 252+ Def Politoed: 110-130 (28.6 - 33.8%) -- 97.7% chance to 4HKO after Leftovers recovery
252+ Atk Mega Aggron Heavy Slam (120 BP) vs. 252 HP / 252+ Def Politoed: 98-116 (25.5 - 30.2%) -- 0.2% chance to 4HKO after Leftovers recovery
252+ Atk Mega Aggron Power-Up Punch vs. 252 HP / 252+ Def Politoed: 45-53 (11.7 - 13.8%) -- possibly the worst move ever
252+ Atk Mega Aggron Iron Head vs. 252 HP / 252+ Def Politoed: 66-78 (17.1 - 20.3%) -- possible 7HKO after Leftovers recovery
252+ Atk Mega Aggron Rock Slide vs. 252 HP / 252+ Def Politoed: 83-98 (21.6 - 25.5%) -- possible 5HKO after Leftovers recovery

-Jolteon w/Choice Specs
Nature: Timid
Ability: Volt Absorb
EVs: 252 Sp.Attack, 252 Speed, 4 HP
Moves: Thunder, Volt Switch, Signal Beam, Hidden Power Ice

Jolteon can handle a rain boosted Scald from Politoed:
4 SpA Politoed Scald vs. 4 HP / 0 SpD Jolteon in Rain: 126-148 (46.3 - 54.4%) -- 59% chance to 2HKO

And the rain makes an OHKO via Thunder a certainty.

Mamoswine @ Choice Scarf
Trait: Thick Fat
EVs: 36 HP / 252 Atk / 220 Spe
Jolly Nature
- Earthquake
- Icicle Spear
- Icicle Crash
- Rock Slide

252 SpA Choice Specs Jolteon Signal Beam vs. 36 HP / 0 SpD Mamoswine: 165-195 (44.5 - 52.7%) -- 25.8% chance to 2HKO

252 Atk Mamoswine Earthquake vs. 4 HP / 0 Def Jolteon: 494-584 (181.6 - 214.7%) -- guaranteed OHKO

Mamo comes in and tanks a Signal Beam from Jolteon, outspeeds and OHKOs with EQ.

Pelipper (M) @ Leftovers
Trait: Rain Dish
EVs: 252 HP / 56 Def / 200 SDef
Calm Nature (+SDef, -Atk)
- Scald
- Stockpile
- Protect
- Roost

Mamoswine would be locked onto Earthquake thanks to Choice Scarf, which has no effect on Pelipper. Pelipper could then switch into the field and take Mamoswine down with a couple of Scalds.

Heliolisk @ Life Orb
Ability: Dry Skin
EVs: 252 Spd / 252 SAtk / 4 HP
Timid Nature
IVs: 30 SAtk
- Thunderbolt
- Surf
- Focus Blast
- Volt Switch

Heliolisk can absorb that scald and strike back with a super effective thunderbolt. Pelliper can't do anything in return.

Swagsire Quagsire w/Leftovers
Nature: Sassy
Ability: Water Absorb
EVs: 252 HP, 8 Defense, 248 Sp.Defense
Moves: Earthquake, Recover, Scald, Toxic

Is immune to 3 of Heliolisk's attacks, and Focus Blast only 3HKOs with this EV spread:
252 SpA Life Orb Heliolisk Focus Blast vs. 252 HP / 248+ SpD Quagsire: 142-168 (36 - 42.6%) -- 94.6% chance to 3HKO after Leftovers recovery

While Earthquake OHKOs.

Roserade @ Black Sludge
Natural Cure
8 HP / 248 Def / 252 SAtk
Bold nature
- Leaf Storm
- Sludge Bomb
- Hidden Power Fire
- Synthesis

0 Atk Quagsire Earthquake vs. 8 HP / 248+ Def Roserade: 90-106 (34.2 - 40.3%) -- 43.6% chance to 3HKO after Black Sludge recovery

Click to expand...

Can switch in and threaten to OHKO.

pirouette said:

Roserade @ Black Sludge
Natural Cure
8 HP / 248 Def / 252 SAtk
Bold nature
- Leaf Storm
- Sludge Bomb
- Hidden Power Fire
- Synthesis

Can switch in and threaten to OHKO.

Click to expand...

Spread is kinda inefficient. Uninvested Leaf Storm still KOs Quagsire. Roserade would rather have all the mixed bulk it can get by investing the other half of its EVs into HP.

Goodra:

-Draco Meteor
-Fire Blast
-Sludge Bomb
-Focus Blast
Nature: Modest
EVs: 248 HP/252 SAtk/8 SDef
Item: Assault Vest
Ability: Gooey

Goodra uses its Assault Vest-boosted Special Defense to sponge whatever Roserade throws at it, then threatens it out with Fire Blast.

-Dragonite w/Weakness Policy
Nature: Adamant
Ability: Multiscale
EVs: 252 Attack, 252 Speed, 4 HP
Moves: Dragon Claw, Dragon Dance, Fire Punch, Extreme Speed

Can take a Draco Meteor thanks to Multiscale:
252+ SpA Goodra Draco Meteor vs. 4 HP / 0 SpD Multiscale Dragonite: 207-244 (63.8 - 75.3%) -- guaranteed 2HKO

Then outspeeds and OHKOs with a Dragon Claw (even without a WP boost).

Heatran @ Leftovers
Trait: Flash Fire
Bold Nature (+Def -Atk)
248 HP / 8 Sp.D / 252 Def
-Lava Plume
-Protect
-Roar
-Toxic

+2 252+ Atk Dragonite Dragon Claw vs. 248 HP / 252+ Def Heatran: 102-120 (26.4 - 31.1%) -- 9.5% chance to 4HKO after Leftovers recovery
252+ Atk Dragonite Dragon Claw vs. 248 HP / 252+ Def Heatran: 51-60 (13.2 - 15.5%) ((If it doesn't have the WP Boost.))

Can proceed to burn or widdle it down with toxic. Or of course, Roar if D-nite tries to set up on it.

Mamoswine @ Life Orb / Choice Band
Trait: Thick Fat
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature

- Icicle Spear
- Ice Shard
- Earthquake
- Superpower / Stone Edge

Mamoswine can bypass Dragonite's Multiscale with Icicle Spear, which is an easy OHKO, while Dragon Claw fails to 2HKO (although it could end up being a tie if Mamo switches directly into Dragon Claw due to LO recoil, to fix it a CB may be used over it).

Cresselia (F) @ Leftovers
Trait: Levitate
EVs: 252 HP / 252 Def / 4 SAtk
Bold Nature (+Def, -Atk)

• Moonlight
• Calm Mind
• Psychic
• Ice Beam

4 SpA Cresselia Psychic vs. 4 HP / 0 SpD Mamoswine: 117-138 (32.3 - 38.1%) -- 95.2% chance to 3HKO

252+ Atk Life Orb Mamoswine Ice Shard vs. 252 HP / 252+ Def Cresselia: 60-71 (13.5 - 15.9%) -- possibly the worst move ever
252+ Atk Life Orb Mamoswine Superpower vs. 252 HP / 252+ Def Cresselia: 58-70 (13 - 15.7%) -- possibly the worst move ever
252+ Atk Life Orb Mamoswine Icicle Crash vs. 252 HP / 252+ Def Cresselia: 126-149 (28.3 - 33.5%) -- 97.1% chance to 4HKO after Leftovers recovery
252+ Atk Life Orb Mamoswine Stone Edge vs. 252 HP / 252+ Def Cresselia: 99-117 (22.2 - 26.3%) -- possible 5HKO after Leftovers recovery

Houndoom (F) @ Leftovers
Trait: Early Bird
EVs: 4 HP / 252 SAtk / 252 Spd
Modest Nature (+SAtk, -Atk)
- Taunt
- Dark Pulse
- Nasty Plot
- Flamethrower

Taunt locks Cresselia into using Ice Beam and Psychic. Houndoom takes no damage from the latter due to its Dark typing. If Cresselia were to use Calm Mind on the turn Houndoom is switched in, Houndoom can use Taunt to prevent it from boosting its Special Defense stat any further and 2HKO with Dark Pulse after using Nasty Plot once. Taunt will also prevent Cresselia from recovering its lost HP with Moonlight.

+2 252+ SpA Houndoom Dark Pulse vs. +1 252 HP / 0 SpD Cresselia: 270-320 (60.8 - 72%) -- guaranteed 2HKO after Leftovers recovery

+1 4 SpA Cresselia Ice Beam vs. 4 HP / 0 SpD Houndoom: 46-55 (15.7 - 18.8%) -- possible 8HKO after Leftovers recovery

Everyone's favorite...wait, what exactly is Tyranitar based off of? its a Godzilla thing XD

-Tyranitar w/Choice Band
Nature: Adamant
Ability: Sand Stream
EVs: 252 HP, 252 Attack, 4 Sp.Defense
Moves: Stone Edge, Crunch, Earthquake, Brick Break

You know what happens, right?