Blastoise did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Blastoise is an anthropomorphic turtle with a very stout appearance. It's skin is mainly blue and it's shell is mostly dark brown and thick. A Blastoise has two pumps coming out of its shell to shoot out high-power blasts of water. Proven, these blasts can punch through very thick steel. It stands as tall as 5' 3" and weighs 188.5 pounds. It is a Generation I Starter Pokémon.