You mean Skuntank support? ("Slowking with Slowking support")
Yes, it is indeed cool. It's an instance where the element of surprise is actually rather practical. In addition to OHKOing Slowking most of the time whether or not you predict the switch (speaking from personal experience using it, since most people eschew defense investment in favor of HP), you can also punch a decent hole into certain slower with HP Grass and can spread burn around. As I said before, it makes a decent scout to see how opponents respond to the first Fire type they see. You could also try Return in the last slot if you're paranoid of enemy Fire types, as an opposing Magmortar 2HKOs your own Maggy and Typhlosion with its STAB. Most of the Magmortars I've fought usually like to spam fire moves, so an immunity of your own is always welcome, and if you're really lucky you could get a free choiced Flash Fire boost from Fire Blast. Fire Fire and Oveheat are awesome, though sadly you're stuck with unreliable STAB.
Those are the only two, yes, but you'll need a spinner so you might not have the appropriate Pokemon on the field to prevent them from setting up and dealing with them accordingly. Since I'm guessing the Fire types are supposed to be late game Pokemon, and rocks might not always be off the field, and they could be worn down fast. Of course, that might just be my paranoia at having to check absurdly common threats be talking, so you could just ignore that lol.