Flash Fire Chandelure is better than Heatran in one very specific way: Blaziken and Infernape.
In Ubers or OU, it is a pretty hard counter to both of those, I would say. Immune to both their STABs, and with good defenses to handle Hidden Powers.
It can't handle a Stone Edge, but with a berry or a Sash, or maybe even a Scarf depending, it will be able to take them down with a Shadow Ball.
Carry Energy Ball around to deal with a TTar switch in and you're looking at a pretty good Pokemon that doesn't need Shadow Tag to be viable.