Heatran is used for its signature move Megan Storm, but is it really that useful? And is yes, how do I use it?
Heatran has amazing defensive utility thanks to its typing and Flash Fire, which make it immune to sandstorm, Toxic, and Fire-type attacks. These qualities let it check Steel- and Grass-types like Ferrothorn, Skarmory, Amoonguss, and Jirachi very well. Heatran also has great support options like Stealth Rock, Toxic, Will-O-Wisp, and Taunt that it can easily mix and match to effectively support its team, as its sets aren't very team dependent. Its offensive presence is also fantastic thanks to high-Base Power moves like Magma Storm and Earth Power, which let it punish and effectively wear down its checks such as Water-types, Garchomp, and Tyranitar. However, Heatran has a noticeable lack of recovery outside of Leftovers that makes it very vulnerable to entry hazards, which makes it more difficult to switch into and consistently check what it needs to. This problem is further compounded by the fact some Pokemon that Heatran can normally beat such as Volcarona run coverage specifically for it, which leaves it quite pressured. Another issue is that some of the best Pokemon in the metagame, including Excadrill, Garchomp, and especially Politoed, all threaten Heatran immensely.
It has nice typing and ability. It can also effectively toxic stall and setup stealth rocks. Smogon gives quite a nice explination Here
