Which dog is the king of dog?

Poodle "Toy" is not a breed but, rather, is a sub miniature (the smallest-sized) variety of a breed. So, for example, standard, miniature, and toy (from largest to smallest) are all varieties of the same breed, poodles. There would be nothing besides size itself, to prevent either variety from interbreeding with another to produce a new poodle. Numerous breeds of domestic dogs come in different size varieties, just as does the poodle.