Approved by @Aragorn the King.
Original thread here.
Format stolen from @DarkNostalgia's thread

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#483 - Heatran
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"The Lava Dome Pokemon"

Base Stats:

91 HP / 90 Atk / 106 Def / 130 SpA / 106 SpD / 77 Spd

Abilities:

Flash Fire: Activates when user is hit by a damaging Fire-type move (including Fire-type Hidden Power). Once activated, user’s Fire-type moves deal 1.5 times damage. While this ability is in effect, this Pokémon is immune to damage from Fire-type attacks and Fire-type Hidden Power (accuracy and effect from these moves are ignored).

Flame Body: The opponent has a 30% chance of being induced with Burn when using an attack, that requires physical contact, against this Pokémon.

Notable Moves
(STAB moves are in Grey)

Taunt
Flamethrower
Fire Blast
Will-O-Wisp
Solarbeam
Substitute
Toxic
Stone Edge
Flash Cannon
Earth Power
Stealth Rock
Lava Plume
Protect
Roar
Overheat
Ancientpower

Analysis:

Heatran has always been on top of the usage stats since it's inception in Gen IV & for very good reason.  Heatran has several numerous traits that distinguish it from every other Pokemon in the meta.  An excellent Fire / Steel typing grants it 9 resistances (5 4x resistances) & one immunity.  It's amazing ability in Flash Fire allow it to switch into Fire types with little to no effort at all.  Fantastic 91 / 106 / 106 bulk backed up by the fantastic typing allows Heatran to withstand a plethora of assaults from a wide variety of special & physical attackers, including Gardevoir Mega, Gengar, Latias/os, Manetric Mega, Rotom-W, & Talonflame.

However, it's not all positives for Heatran.  With the Steel nerf coming with XY / ORAS, Heatran is no longer resistant to Dark & Ghost type attacks, making him much more vulnerable to them.  A nasty weakness to the common Water, Fighting, & a 4x weakness to Ground type attacks makes Heatran extremely miserable.

Movesets:

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"Fast Support"
Heatran @ Leftovers
Ability: Flash Fire
EVs: 248 HP / 8 SpA / 252 Spe
- Lava Plume
- Taunt
- Toxic
- Stealth Rock

This set takes advantage of Heatran's above average speed & solid bulk in order to be an effective stall-breaker against slower, bulkier teams.  Lava Plume is a solid, spammable STAB move with a nice 30% chance to burn the opponent.  Taunt is an excellent move on this set, allowing it to stop several set up sweepers in their tracks, most notably Calm Mind Clefable, & prevents it from regaining health VIA Wish, Soft-boiled, & Moonlight.  Toxic is useful to cripple bulky water types, the most notable of which being Rotom-W.  Stealth Rock is an obvious move as Heatran is an extremely solid user of the move.

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"Offensive Stallbreaker"
Heatran @ Leftovers / Air Balloon / Power Herb
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Magma Storm
- Earth Power
- Taunt
- Toxic / Solarbeam

Most people will usually switch in Pokemon such as Chansey & Mew in on Heatran in order to stop it.  Magma Storm is an excellent move that traps Pokemon that cannot harm Heatran, effectively trapping them for 4 - 5 turns.  Earth Power nails opposing Heatran (Assuming no Air Balloon), Tentacruel, & Mega Diancie.  Taunt is an excellent move that prevents opponents trapped by Magma Storm from healing up, allowing Heatran to slowly whittle it down with Magma Storm / Earth Power.  Toxic is a solid move to take out common switch ins to Heatran, once again, the most notable of them being bulky Water types.  Solarbeam is an interesting option in order to lure in & KO Keldeo & Azumarill.

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"Specially Defensive"
Heatran @ Leftovers
Ability: Flash Fire
EVs: 248 HP / 192 SpD / 68 Spe
Calm Nature
- Lava Plume
- Toxic
- Taunt / Roar
- Stealth Rock / Protect / Earth Power

This set makes use of Heatrans excellent defensive typing along with a plethora of resistances in order to be a solid Specially Defensive tank.  Lava Plume once again is the STAB move of choice, with a 30% chance to burn the opponent.  Toxic once again is used to hit bulky water types, most notably Azumarill, Keldeo, & Rotom-W on the switch in.  Taunt halts CM Clefable from setting up on it, while also shutting down most defensive Pokemon's recovery.  On the other hand though, Roar is a viable phasing move, removing boosts from set up sweepers.  If another teammate on the team is already using Stealth Rock, Protect is an excellent option to grab a free turn & rack up Burn & Toxic damage, while also being used to scout sets.  Earth Power prevents other Heatran from out-stalling this set with Taunt & makes dealing with Charizard Mega X much easier.

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"Offensive"
Heatran @ Air Balloon
Ability: Flash Fire
EVs: 12 HP / 252 SpA / 244 Spe
Timid Nature
- Fire Blast
- Taunt
- Toxic / Earth Power
- Stealth Rock

This Heatran set makes for a solid lead for offensive teams, allowing them to get a quick Stealth Rock up.  Fire Blast is an insanely powerful STAB move with a slight chance to burn & can 2HKO Sableye Mega that lack Special Defense investment.  The combination of Taunt + Toxic is a brutal stallbreaking combination that prevents Heatran from being walled by Pokemon such as Chansey & also cripples bulky Water switch ins.  However, Earth Power is an option if you're paranoid about opposing Heatran, & Tyranitar stonewalling you.  Finally, Stealth Rock is Heatran's main use as an offensive Pokemon & will usually get them up before your opponent will.

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"Choice Scarf"
Heatran @ Choice Scarf
Ability: Flash Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Overheat / Fire Blast
- Flash Cannon
- Earth Power / Hidden Power Ice
- Stone Edge / Ancient Power

This set works best as a hit & run attacker, making very good use of Heatrans deep move-pool & solid Speed stat to turn it into a fantastic revenge killer / cleaner.  Overheat is used for nuking everything that doesn't resist it & Keldeo can't even switch in twice without being 2HKOd.  However, Fire Blast is used if you want your Heatran to clean up late game.  Flash Cannon nails most Fairy Types, Latios, Tyranitar, & Terrakion for super effective damage.  Earth Power gets super effective damage on Charizard Mega X & opposing Heatran.  On the other hand, Hidden Power Ice can be used if hitting Dragonite, Garchomp, Landorus-I / T & Gliscor for super effective damage is in your interest.  The last slot goes to either Stone Edge or Ancientpower & is up to preference.  Stone Edge OHKOs both Charizard Mega Y & Talonflame, while Ancientpower hits extremely hard off of Heatran's high Special Attack stat.

Conclusion:

Heatran has been one of those Pokemon that have been the cream of the crop for an extremely long time.  How has the advent of ORAS affected Bisharp?  With several powerful offensive & Mega Pokemon in the tier, can Heatran remain as one of the most consistent Pokemon in the tier?