ALTARIA. Listen, I know it isn't the strongest Dragon-type, but how could I resist the big poofy cloud bird? When I think of my favorite Pokemon, there are usually two different ways I think about them: 1) Do I like them in-game? or 2) Do I want to be their friend irl? And Altaria is firmly in the second camp. I want to take a nap on its cloud (or cloud-like feathers? unclear lol)
My favorite type of mythological creature is any huge underwater beast. I'm talking your sea serpents, your leviathans, your scylla/charibdises, the Loch Ness Monster (and her cousin Champ) - basically if it's huge and terrifying and hiding just beneath the waters surface, or in the vast deep where humans cannot tread, I am all about it.