Rapidash is awesome. After some more testing I broke 1300 with Rapidash. The CB set hits like an absolute truck, 2HKOing stuff like Charizard outside of Sun without a Flash Fire boost. Wild Charge can hit stuff like Wartortle, while Low Kick can be used for Golem/Regirock, 2HKOing them both. Quick Attack can really come in handy as well, especially against weakened rain teams. The set has so much utility, being so fast and having that Fire immunity, it creates an excellent pivot if you feel like double switching, or you can just smash anything not named Flareon with Flare Blitz.
Because of its excellent Speed it often cleans up late game, and I've been using CB Braviary (another incredible mon) to lure and weaken Rock types so that Rapidash can sweep later. The two make a great pair, 2HKOing the entire tier if you can predict correctly. Definitely more effective than Kecleon.
I will post a more in depth analysis if I can be bothered to get any higher, but for now here is the screenshot: