#650 Chespin
#651 Quilladin
#652 Chesnaught
#653 Fennekin
#654 Braixen
#655 Delphox
#656 Froakie
#657 Frogadier
#658 Greninja
#659 Bunnelby
#660 Diggersby
#661 Fletchling
#662 Fletchinder
#663 Talonflame
#664 Scatterbug
#665 Spewpa
#666 Vivillon
#667 Litleo
#668 Pyroar
#669 Flabébé
#670 Floette
#671 Florges
#672 Skiddo
#673 Gogoat
#674 Pancham
#675 Pangoro
#676 Furfrou
#677 Espurr
#678 Meowstic
#679 Honedge
#680 Doublade
#681 Aegislash
#682 Spritzee
#683 Aromatisse
#684 Swirlix
#685 Slurpuff
#686 Inkay
#687 Malamar
#688 Binacle
#689 Barbaracle
#690 Skrelp
#691 Dragalge
#692 Clauncher
#693 Clawitzer
#694 Helioptile
#695 Heliolisk
#696 Tyrunt
#697 Tyrantrum
#698 Amaura
#699 Aurorus
#700 Sylveon
#701 Hawlucha
#702 Dedenne
#703 Carbink
#704 Goomy
#705 Sliggoo
#706 Goodra
#707 Klefki
#708 Phantump
#709 Trevenant
#710 Pumpkaboo
#711 Gourgeist
#712 Bergmite
#713 Avalugg
#714 Noibat
#715 Noivern
#716 Xerneas
#717 Yveltal
#718 Zygarde
#719 Diancie
#720 Volcanion
#721 Hoopa

Mega Evolutions
#3A Mega Venusaur
#6A Mega Charizard X
#6B Mega Charizard Y
#9A Mega Blastoise
#65A Mega Alakazam
#94A Mega Gengar
#115A Mega Kangaskhan
#127A Mega Pinsir
#130A Mega Gyarados
#142A Mega Aerodactyl
#150A Mega Mewtwo X
#1500B Mega Mewtwo Y
#181A Mega Ampharos
#212A Mega Scizor
#214A Mega Heracross
#229A Mega Houndoom
#248A Mega Tyranitar
#257A Mega Blaziken
#282A Mega Gardevoir
#303A Mega Mawile
#306A Mega Aggron
#308A Mega Medicham
#310A Mega Manectric
#354A Mega Banette
#359A Mega Absol
#380A Mega Latias
#381A Mega Latios
#445A Mega Garchomp
#448A Mega Lucario
#450A Mega Abomasnow

Diancie is Rock/Fairy, 2'04", 19.4 lbs. #151. It is known as the Jewel Pokemon. "It can instantly create many diamonds by compressing the carbon in the air between its hands."
Diancie's signature move is Diamond Storm, a physical Rock-type attack. A bunch of diamonds are created and thrown at the enemy. "The user whips up a storm of diamonds to damage opposing Pokemon. This may also raise the user's Defense stat." It has 100 power and 95% accuracy. Diancie can also learn Moonblast, Safeguard, and Light Screen.
Diancie is not related to Carbink on its Pokedex evolution page. However it could be a Manaphy/Phione situation. Or maybe the diamonds it throws turn into Carbink after a couple million years?
At Level 100 with no EV training, Diancie's stats can be 222/236/300/236/344/135.
Hoopa in Pokemon X and YHoopa is Psychic/Ghost, 1'08", 19.8 lbs. #152. It is known as the Mischief Pokemon. "It gathers things it likes and pushes them through its loop to teleport them to a secret place."
Hoopa's signature move is Hyperspace Hole, a special Psychic-type attack. A dark hole is created in the ground, Hoopa goes through it, then comes out behind the enemy and hits them. "Using a hyperspace hole, the user appears next to the target and strikes. This also hits a target using Protect or Detect." It's got 80 power and N/A accuracy. Hoopa can also learn Psychic, Shadow Ball, and Trick Room
At Level 100 with no EV training, Hoopa's stats can be 301/231/154/315/296/177.
Volcanion in Pokemon X and YVolcanion is Fire/Water, 5'07", 429.9 lbs. #153. "It expels its internal steam from the arms on its back. It has enough power to blow down a mountain."
Volcanion's signature move is Steam Eruption, a special Water-type attack. "The user immerses the target in superheated steam. This may also leave the target with a burn." It's got 110 power and 95 accuracy. Volcanion can also learn Flare Blitz, Overheat, and Explosion.
Volcanion is related to the Lumiose City blackouts.
At Level 100 with no EV training, Volcanion's stats can be 275/254/276/247/235/176.
Mega Latios and Latias in Pokemon X and YThere are no other Mega Evolutions in the game aside from Mega Latios and Mega Latias, which look the same. They both retain their original Dragon/Psychic typing.