What are the best natures for the Eeveelutions in Pokemon X and Y?

Answer 1

Here's some of the common natures used in the Eeveelutions:

Vaporeon

Bold - Since it increases Vaporeon's low Defense, it can tank more damage from opposing Pokémon. It can be complemented with Defense EV's;

Modest - This nature takes advantage of its base Special Attack stat.

Jolteon

Timid - This nature increases Jolteon's already high base Speed to make sure it doesn't get outsped by many Pokémon.

Flareon

Adamant - Takes advantage of Flareon's high base Attack stat;

Calm - While it cuts Flareon's Attack, it boosts its Special Defense stat and can let it be more of a supporter with Wish, Protect, Heal Bell/Roar/Toxic and a Special Fire-type move like Lava Plume or Flamethrower.

Espeon

Timid - A Timid nature to increase Espeon's base Speed stat even more and then max out its Special Attack EV's. If you're going with the moves Reflect and Light Screen, then switch the Sp. Attack Ev's with HP instead;

Bold - Common with the use of Baton Pass.

Umbreon

Calm - Suggested nature to make Umbreon a Wish supporter.

Leafeon

Jolly - It increases Leafeon's Speed so it can make use of Swords Dance before attacking the next turn;

Impish - A nature to take advantage of Leafeon's high base Defense stat.

Glaceon

Quiet - Since this nature cuts Glaceon's already low base Speed stat, it can shine with a Trick Room team, while boosting its high Special Attack stat;

Modest/Timid - With max EV's in Speed and holding the Choice Scarf, you can make some damage to your opponent, with the downside of it only being allowed to use a single move unless you switch out. The Modest nature boots its Special Attack stat while the Timid nature boosts its Speed.

Sylveon

Bold - Similar to Vaporeon, this allows Sylveon to tank more damage due to its low base Defense stat;

Modest/Timid - These natures work best with Life Orb and when using Calm Mind in the first turn.

Eevee

When using it at the Little Cup tournaments:

Jolly/Adamant - When holding Choice Band;

Naive/Hasty - When holding Life Orb and using the move Work Up, it allows it to be a mixed attacker.