I was interested to legitimately get Eternal Flower Floette and her signature move too
It is currently unknown whether Game Freak will ever release the Eternal Flower Floette. So, if you want a legitimate Eternal Flower, it is currently impossible. One event I think may lead Game Freak to release the Eternal Flower Floette is if they ever get around to making Pokémon Z, the rumoured sequel game to X and Y.
Source: https://www.thegamer.com/gen-vi-vii-pokemon-still-unreleased/#:~:text=Eternal Flower Floette has a unique cry and,but it was never released to the public.