While Glaceon is a powerful Pokémon, it's not classified as Legendary in the Pokémon universe. Legendary Pokémon are typically rare, powerful creatures with unique abilities and lore. Glaceon is an evolution of Eevee, which is a common Pokémon.
However, it's important to remember that the "Legendary" designation can be applied to specific cards in the Pokémon Trading Card Game, even if the Pokémon itself isn't a Legendary in the main Pokémon games. So, while Glaceon itself isn't a Legendary Pokémon, a specific Glaceon card might be considered Legendary in the TCG.