Heatran outspeeds Donphan and deals 74.4-87.7% damage with Fire Blast -> guaranteed 2HKO if the switch-in is predicted correctly
Donphan OHKOs Heatran with Earthquake

Hippowdown @Leftovers ("OU Specially Defensive")
252 HP / 252 SpDef - Careful nature

Heatran outspeeds Hippowdown and deals 49.5-58.5% damage with Fire Blast -> potential 2HKO if the switch-in is predicted correctly and both attacks roll high damage (due to Hippowdon's Leftovers)
Hippowdon OHKOs Heatran with Earthquake

Garchomp @Rocky Helmet ("OU TankChomp")
252 HP / 252 Speed - Jolly nature

Garchomp outspeeds Heatran and OHKOs with Earthquake
If the switch-in is predicted correctly, Heatran deals 92.8-110.2% with Hidden Power [Ice], which is almost a guaranteed OHKO with Stealth Rock
More offensive sets with no HP investment are a guaranteed OHKO if the switch-in is predicted correctly

Torterra (doesn't really matter which set)

Heatran outspeeds Torterra, and even with maxed HP and SpDef and a +SpDef nature, Fire Blast deals 94.9-112.9%. Without the +SpDef nature, it's a guaranteed OHKO
However, if Torterra gets to attack, Earthquake will OHKO Heatran

Quagsire @Leftovers ("1v1 Stall")
252 HP / 160 Def / 96 SpDef - Impish nature

Heatran outspeeds Quagsire and deals 66.8-79.2% with Earth Power, a guaranteed 2HKO if the switch-in is predicted correctly
This Quagsire set usually has Bulldoze, which only deals 66.8-79.2% damage, but an Earthquake would OHKO
With Hidden Power [Grass], Heatran OHKOs. Even max SpDef EVs would only lower the damage to 89.8-106.8%, which is still a potential OHKO

Gastrodon @Leftovers ("OU Specially Defensive")
252 HP / 252 SpDef - Calm nature

Heatran outspeeds Gastrodon and deals 65.9-78.1% with Hidden Power [Grass], which would be a guaranteed 2HKO, but Earth Power (if HP [Ice] is chosen) only deals 24.4-28.8%
This Gastrodon set usually has Chilling Water as its only offensive move, which only deals 30.3-35.9% damage. Were it to run Earth Power (or Earthquake with a Careful nature), it could OHKO Heatran.

Mamoswine @Focus Sash ("OU Stealth Rock")
252 Attack / 252 Speed - Jolly nature

Mamoswine outspeeds Heatran and OHKOs with Earthquake
If Heatran predicts the switch-in correctly, it can OHKO with Fire Blast

Sandy Shocks @Heavy-Duty Boots ("OU Offensive Pivot")
252 SpAtk / 252 Speed - Modest nature

Sandy Shocks outspeeds Heatran and OHKOs with Earth Power
If Heatran predicts the switch-in correctly, Fire Blast will only deal 85.5-101.6%, which makes an OHKO unlikely

Iron Treads @Leftovers ("Uber Specially Defensive")
252 HP / 252 SpDef - Careful nature

Heatran outspeeds Iron Treads and OHKOs with Fire Blast
If Iron Treads has maxed out speed (e.g. the "OU Offensive" set), it will outspeed Heatran and OHKO with Earthquake

Ursaluna @Flame Orb ("OU Swords Dance")
116 HP / 252 Atack / 140 Speed - Adamant nature - ability: Guts

Heatran outspeeds Ursaluna and deals 65.5-77.4% with Fire Blast, a guaranteed 2HKO if the switch-in is predicted correctly
Ursaluna can OHKO Heatran with Headlong Rush, and if Guts is activated, even an unboosted Facade might OHKO with 87.6-103% damage

Clodsire @Leftovers ("OU Defensive")
248 HP / 252 SpDef / probably 8 Def I forgot - Careful nature

Heatran outspeeds Clodsire but only deals 39.9-47% with Earth Power
Cladsire can OHKO Heatran with Earthquake

Conclusion: Heatran heavily relies on predicting switch-ins correctly to stand a chance against most of these Pokemon. In a one-on-one without switch-ins, Torterra is the only safe win (assuming Fire Blast hits), a win against Iron Treads depends on its set, and a win against Gastrodon is only possible if Heatran is run with HP [Grass]. The meme therefore checks out. Let me know if I missed anything because I haven't done any competitive stuff since Gen 5 :3

[–] TheBlue22@lemmy.blahaj.zone 7 points 1 year ago (1 children)

Jesse what the fuck are you talking about

[–] LordAmplifier@pawb.social 7 points 1 year ago

When you were partying, I studied Pokemon VGC recordings. When you were having premarital sex, I mastered the Gen 4 OU and Uber meta. While you wasted your days at the gym in pursuit of vanity, I cultivated Pokemon on an old Heartgold cartridge. And now that the world is on fire and Team Rocket is at the gate, you have the audacity to come to me for help.

[–] chumbalumber@lemmy.blahaj.zone 2 points 1 year ago* (last edited 1 year ago) (1 children)

I would add the minor point that I've also seen heatran running air balloon instead of life orb, which might change some of the matchups a little bit :)

[–] LordAmplifier@pawb.social 2 points 1 year ago

Right, Air Balloon was all the rage back in Gen 5 and I completely forgot about it! Thanks for pointing it out :3

The reduced damage from it might turn some 2HKOs into 3HKOs, but as long as Heatran outspeeds the opponent (e.g. Hippowdon), that should be fine because they'll probably waste a turn figuring out it has a Balloon and then need another turn to pop it.

[–] cabb@lemmy.dbzer0.com 2 points 1 year ago* (last edited 1 year ago) (1 children)

Hidden Power doesn't exist in Gen 9. Although you can use Tera Blast with the appropriate Tera type to replicate that. Note that using your Tera on Heatran will also change your defensive typing for the 3 turns (?) it lasts.

[–] LordAmplifier@pawb.social 1 points 1 year ago

It's good to know that Hidden Power doesn't exist in Gen 9, thank you :3

Heatran would probably stand a slightly better chance against some of them with Tera types, I reckon. Tera Grass would give it a Ground resistance (Flying would make it immune, but then it'd be vulnerable to Rock-type moves and have no way to deal significant damage), and Grass-type Tera Blast would safely 2HKO Hippowdon, for example. Even a mono-Fire typing would allow it to survive Hippowdon's Earthquake and, with some luck, 2HKO with Fire Blast.