I find Milotic to be one of the most beautiful. It has a really beautiful and pleasant cry, and its design is very appealing on the eyes. And its first evolution method involves maxing out its Beauty stat, so I guess that counts, too XD Then there's Glaceon, Vaporeon, Espeon, and Sylveon. Glaceon I find to be beautiful in cry and color palette (especially its shiny color palette); its design is really lovely as well. Vaporeon is a mix of elegant and beautiful; like Glaceon it has a nice cry, design, and shiny color palette, and its eyes add to its beauty. Espeon is somewhat more elegant (and maybe a bit classy?) with its design and normal color palette. Sylveon is one of the cutest Pokemon I've ever seen, but it also has a hint of elegance with its ribbonlike feelers. Oh, and Ninetales, of course! It's very beautiful and elegant design-wise, and has really appealing normal and shiny color palettes.