pokemon is a japanese franchise. it is irrelevant to bicker about western mythology and western understanding of science, the only thing that matters with regards to its influences and meanings is japanese culture and opinion.
it is for this reason that cyndaquil, clearly a hedgehog or echidna, is known as the 'fire mouse' pokemon, despite neither of those animals being remotely close to rodents. in japanese, a hedgehog is called a 'needle mouse', which is why a hedgehog respresents the japanese mythological creature the 'hinezumi', the fire mouse. japanese perception is the only thing that counts when it comes to pokemon.
with that established, the japanese name for crocodile is 'wani'. this is also understood to mean 'sea serpent'. in japan, crocodiles and see serpents are equivalent linguistically.
skeledirge is the snake.