There aren't enough fire types.
What we need are big feathered serpents, the final evolution of which breathes fire and is half flying or half dragon.
They are loosely based (design-wise) off of fireworks. The basic is like those little charcoal-colored snakes that you light, the ones that grow and grow.
The stage one is larger, and more colorful, with some adornments radiating like fireworks would in the sky. I was thinking rudimentary feathered wings (not large enough to fly with though) that would then grow large and strong in the stage two. Maybe open flames incorporated somewhere.
The final evolution, I imagine a ferocious Quetzlcoatl like creature, looking like the lovechild of Rayquaza and Ho-oh. I don't think it should necessarily have the small limbs like Rayquaza though, emphasizing that it is a snake,right? There could be open flames radiating from the neck or torso, heck, I don't know. Something resplendent and intimidating, like a big dramatic firework display, right?
I'm not sure if these should be given snakelike mouths with fangs or birdlike heads with beaks. While the former seems more natural, and easily drawn, I think the latter would help make them a little more unique. There are lots of bird pokemon, and lots of snake pokemon, but not too many birdheaded-snakebodied pokemon.
I'm not much of an artist (my attempts at these were terrible) but if any of the talented people here want to take a stab at it, please do. I'd be really interested to see what you come up with.
A similar design could be an electric type flying serpent imo, swapping the firework design for one more akin to lightning bolts. Now I'm thinking something that looks like a fusion of Rayquaza and Manectric. Not sure what to do for the basic and/or stage one, but as a final evolution I can just imagine a huge glowing yellow/electric blue snake, lighting up the night sky. I know there are people who come on here that have tons of artistic talent, if you need any ideas to bring to life, this could be one of them.
