The Krawk. There's only 2,368 of them in Neopia. http://neopets.com/topneopets.phtml There's a link that'll tell you how many of each neopet species there are in Neopia.
That link does show the most popular created pets, but as it states on the page it doesn't count any pets that have been morphed using a potion or any pets that have been changed by the lab map. So, the real values are different to what is shown on there.
I think it does show that, because see next to the name of the pet, it says the number of pets there are, and then next to THAT it says "out of ____"? The "out of" number is the number of them that Neopets has made available themselves to people, and the number of pets that exceeds that number is the number of pets that have been morphed. At least, that's what makes sense to me.
directly from the top of the page This page lists the most popular created Neopets. (This doesn't count morphed or labbed Neopets!)
Oh jeez, my mistake! Sorry! >.< I guess it helps to read every bit of text from top to bottom! :arf: Either way, there's the most popular pets.
The extra bits will have come from when on Cybunny day more are released, a huge rush of people go to create a pet at the same time, and it just spills over a little. That's what I'd assume.
The Krawk. I think you need to buy a Krawk petpet and go to a cave or something to make one. Or you could just get a Krawk TP or MP.
Draik's and Krawk's are a given, but if it was a toss-up between the two I'd have to say Krawk. Draik's can be created through eggs and MPs, both of which are around the same price. Krawk's however, can be created through the PetPet(4Mill) or MP's(Need price check.). Krawk's are more expensive than Draik's, therefor I think that Krawk's are the rarest pet.
I've been planning to get a Krawk to get the avatar. Instead, I spent 3mil to get a Trans Draik Potion. I think he looks cooler than Krawk.