I'm assuming that you're talking about Battle Stadium Singles here.
Heatran is not the best steel type for TR, nor is it a great TR abuser, but it can still be a reliable as a great defensive pivot on TR teams while serving as an excellent pair to some users like Hatterene. Its speed tier is okay to use in a TR team, however, it still will remain outsped in Trick room by some wallbreakers and most defensive mons.
Here are some reasons to use Heatran on a TR team:
1. Defensive typing makes up and covers weaknesses for TR teams. Most notably for Hatterene.
2. Can trap opponents to allow the user to swap to a heavy hitter thats hard to bring in, such as Ursaluna, using magma storm.
3. Great defensive utility with Will-O-Wisp and Stealth Rock.
Here are some reasons not to use Heatran:
1. Damage is too unreliable to keep up with the average destructive damage of a TR team.
2. Cannot outspeed defensive mons in TR.
3. Dragon types with ground type moves are very common in BSS.
After explaining this, I recommend to not use Heatran in a TR team, as many Pokemon can hit harder and still have better defensive utility than Heatran.