Pokemon City

Ninetales - Drought (Permanent sunlight, unless another weather ability is used)
Nature: Modest (+SpAtt/-att)
EVs: 252 Att, 252 Spd
Item: Leftovers
Moves: Fire Blast, Energy Ball, Toxic, Will-O-Wisp

Ninetales' purpose is to keep Drought up longer than opposing Weather Pokemon can, such as Hippowdon, Tyranitar and Politoed. This mostly entails out-living the other weather Pokemon.
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Leafeon - Chlorophyll (Doubles speed in Sunlight)
Nature: Adamant (+Att/-SpAtt)
EVs: 252 Att/Spd
Item: Life Orb
Moves: Sword Dance, Leaf Blade, Quick Attack, X-Scissor

Leafeon's job is to kick *** and take names. I previously used a physical Venusaur here, because it threw people off. Unfortunately, being poison made it neutral to ground type, so Hippowdon and Tyrantitar ate it alive with Earthquake. And Leafeon's just more of a sweeper build than Venusaur ever was. Destroys Latios and Latias.
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Typhlosion - Flash Fire (Absorbs a fire move to increase the power of fire moves)
Nature: Timid (+Spd/-Att)
EVs: 252 SpAtt/Spd
Item: Choice Specs
Moves: Eruption, Focus Blast, Solar Beam, Hidden Power Ice

Typhlosion is by far the best non-Uber Fire-Type special attacker and has replaced my Charizard due to Eruption being an absolutely monstrous attack.
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Hitmontop - Technician (Boost attacks with a base power of 60 or below)
Nature: Adamant (+Att/-SpAtt)
EVs: 252 HP/Att
Item: Leftovers
Moves: Rapid Spin, Mach Punch, Bullet Punch, Sucker Punch

Best spinner I've used yet and takes care of pesky Tyranitars and Blisseys. Technician boosts Bullet Punch and Mach Punch to respectable damage to justify using them. Sucker Punch destroys most psychic and ghost types. Fairly Bulky. Skarmories are an issue.
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Victini - Victory Star (Increases accuracy of allies moves by 1.1x)
Nature: Jolly (+Spd/-SpAtt)
EVs: 252 Spd/Att
Item: Choice Band
Moves: V-Create, Zen Headbutt, Fusion Bolt, U-Turn

Physical powerhouse. V-Create is the strongest Fire Attack, and one of the strongest physical attacks in the game. Purpose is to destroy everything it can.
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Cloyster - Skill Link (Auto-maxes a multi-hit attacks attack rounds)
Nature: Adamant (+Att/-SpAtt)
EVs: 252 Att/Spd
Item: Focus Sash
Moves: Shell Smash, Icicle Spear, Rock Blast, Explosion

Dragon, Flying and Ground type buster. Messes plenty of others up too. Shell Smash is a very very powerful stat boosting move. If anything, Icicle Spear is pretty much guaranteed to kill any dragon type I hit, including multiscale Dragonite. Explosion is clearly a last resort.