Elite Four Champion: Diantha - Pokemon X and Y

Elite Four Champion Diantha 

Diantha has a full team of six Pokemon; Hawlucha, Tyrantrum, Aurorus, Gourgeist, Goodra & Mega Gardevoir

Hawlucha

Level: 64

Types: Fighting/Flying

Ability: Limber

Attacks: Swords Dance, Flying Press, X-Scissor & Poison Jab

Weakness: Psychic, Electric, Ice, Fairy & Flying

Strategy: Hawlucha is able to counter pretty much most Pokemon, an Electric Move will take it down easily.

Tyrantrum

Level: 65
Types: Rock/Dragon
Ability: Strong Jaw
Attacks: Head Smash, Earthquake, Dragon Claw & Crunch
Weakness: Steel, Ground, Dragon, Ice, Fairy & Fighting
Strategy: Head Smash is its signature move but takes a serious hit of recoil, Water-Types can hit hard against it though.

Aurorus

Level: 65
Types: Rock/Ice
Ability: Refrigerate
Attacks: Light Screen, Reflect, Blizzard & Thunder
Weakness: Fighting, Steel, Ground, Water, Rock & Grass
Strategy: Aurorus will attempt to set up Reflect & Light Screen for the rest of the team, but a Water-Type can take it down easily.

Gourgeist

Level: 65
Types: Ghost/Grass
Ability: Pickup
Attacks: Trick-or-Treat, Phantom Force, Seed Bomb & Shadow Sneak
Weakness: Ice, Dark, Flying, Fire & Fire
Strategy: Trick-or-Treat will give you an extra Typing for this battle, giving you Ghost - this can be used in your favour with STAB Attacks or can be used against you if Gourgeist is able to hit you with a Ghost-Type Move.

Goodra

Level: 66
Types: Dragon
Ability: Sap Sipper
Attacks: Dragon Pulse, Muddy Water, Fire Blast & Focus Blast
Weakness: Fairy, Dragon & Ice
Strategy: Goodra I found to the most annoying to get take down, Fairy-Type is the best taking it down though.

Mega Gardevoir

Level: 68
Types: Psychic/Fairy
Ability: Trace
Attacks: Moonblast, Psychic, Thunderbolt & Shadow Ball
Weakness: Steel, Ghost & Poison
Strategy: Once in its Mega Form, it becomes a tank. Being able to counter most Pokemon. Using a Poison-Type Attack with a non-Poison Type Pokemon is the best way of taking it down.

Diantha

Once you defeat Diantha, you will become the new Elite Four Champion. Showing off all your Pokemon is the Pokemon Hall of Fame. You will then get to watch a cutscene where you and the gang are graduated for taking down Team Flare. You will also get to battle against AZ.