Apparently Wartortle's fluffy tail is based on a mythical turtle with a seaweed tail, for having lived a thousand years. Not sure about his ears. (Also some promo artwork miscolors the fluff AS ears, but theyre supposed to be the same off-blue as his tail)

Not sure why artistically he loses that moving up to Blastoise, but it follows the evolutionary theme of consuming the tail for energy (kind of like tadpoles and their tail) and using that energy to create his pressure washers. If anything, Squirtl show have a more apparent tail to convey the presence of such, to intentionally draw attention to its consumption later.

Maybe it is, but I think Blastoise is a way cooler third evolution than Wartortle is a second evolution

I'm not saying it sucks or anything, I just think it's the "worst" of the 3