The Heatran quest is one out of many additional, not story related Legendary Pokémon quests and is the only way to catch the Legendary Pokémon Heatran.
The Heatran quest is the only quest which gives the player a option to choose two different ways to encounter the legendary Pokémon.
Instructional walkthrough
Preparation for the quest
It is recommended to prepare well for this quest as you have to fight through a large area with many trainers in order to be able to catch Heatran. Entering this area requires a Pokémon with a level of 60 or less. Therefore, a good choice of your partner is important.
Depending on which way you choose to catch Heatran, the following Pokémon are often recommended:
You should keep in mind that all Rare Candies and Master Balls will be taken away by a NPC for the duration of the quest. Once the quest has been completed, the NPC will return them.
Stark Mountain
The closest Pokémon Center to Stark Mountain is located in Fight Area, therefore you have to pass trough Route 225, Route 226 and Route 227 in order to enter [Stark Mountain]] and fight through Stark Mountain Entrance Pt to reach Buck and the starting point of the quest. Based on this fact, it is recommended to clear these areas first, as Stark Mountain can only be accessed with a single Pokémon in your team which has a level of 60 or less. Passing through this area without clearing it first may result in unwanted level ups.
Once arrived at Stark Mountain, you can enter the cave. Pass through the first part and talk with Buck. When you hit the requirement of having only one Pokémon in your team which is level 60 or less, the quests starts. Buck will take all Rare Candies and Master Balls from you, you can also not leave this area without canceling the quest. If you do decide to leave, you will need a level 60 or lower Pokémon to enter again. Same goes for fainting inside the mountain.
Once you are in the mountain, you have to cross through it in order to enter the inner cave where Heatran is located. For that, you have to pass through many trainers. To help yourself, you can catch some Pokémon in the cave to be able to heal up your main Pokémon with Revives or other healing items, in case it gets defeated or low on health. Defeating all the trainers can be an advantage, in such a way that the final fight, which must be done after this part of the cave, will be easier. The shortest, meaning the way with the fewest trainers, is shown below.
All trainers and their teams are listed here:
Heatran Quest Main Cavern Pt Trainers |
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Notes: This trainer does not reward any money nor experience. |
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Notes: This trainers Pokémon know various illegal moves, such as Roost and Glare. |
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All NPCs cool down after 7 days unless noted contrariwise. |
Stark Mountain Heatran Pt
Once you have reached Heatran's room, you will have a dialogue scene and have to fight Commander Mars.
 | Commander Mars |
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- Emboldened moves avail from a STAB bonus when deployed by that Pokémon.
- Italicized moves are functionally broken; see their individualized pages for more information.
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Catching Heatran
Now that Commander Mars has been beaten, you can fight Heatran which is level 99 and have the chance to catch it. Doing this won't allow you to sync it or use a Master Ball. Alternatively, you can defeat it in order to talk to Buck who will give you your Rare Candy and Master Balls back and you can leave the cave, to retrieve your desired sync, and re-enter it without any requirements needed. If you choose to defeat it, Heatran will re-spawn in its room but will be level 30 this time.
In case you were unsuccessful in catching Heatran, you can earn a second chance at catching it by beating Nikola.
External Links
Legendary Pokémon Quests Megathread