Revealing that Ninetailes could be Suicune, or that Arcanine could be Raikou, is like all of these "shiny" revelations being majestic and getting you through to more sides of how Pokemon can be and display themselves.
I thought that the best shiny Pokemon is a black Charizard, bathed in the midnight, streaming holographic flapping glitter, crystallizing the kingdom with his flamethrower, adding music and enchantment to the dance floor.
And then a blue shiny Mew looks like the sky, where Ash saw it leaving fairy dust through the clouds before the whole, You and Me were a Miracle song, showing that Mewtwo may indeed have a soft side, and Mew's reflection of Mewtwo as a more critical evolutionary leap may also make Mewtwo more spontaneous and playful, much like Mew descends in danger cones for your novelty to get you to new island where Mewtwo resides.