>>53595391eevee could've been a little more creative then just recolored dog things
water - more otter/sea lion like (maybe some hints of a dolphin or a whale too)
fire - fox
electric - kind of porcupine or echidna like (or a wild cat like a cheetah cause speed but that's a little more boring)
psychic - to be honest i'm fine with espeon's design, it works
dark - tattered looking rabid dog. kind of a mix between a hyena and a regular wolf
grass - maybe something like a smilodon, but overall it's biology should be much more plant-like, with root feet and everything
ice - arctic fox like you said, or maybe something like a lemming
fairy - either a kitsune or a wolf akin to fairy tales involving a wolf
poison - honestly there's a lot of things to pull from. a shrew, a bat, a skunk etc.
flying - flying fox like you said.
ghost - skeletal mammal with spirit flames and everything, or a shadowy jackal based on anubis. maybe it could be based on something extinct?
ground - mole or a gopher or something else that burrows. that's kind of an obvious one
rock - a mountain lion?
steel - based on an armadillo or pangolin with steel armor
fighting - maybe based on a predatory cat or something. could have horns too i guess
dragon - based on prehistoric repto-mammals
bug - based on an anteater or aardvark