New Pokémon:

There are supposedly 130 new Pokémon
Chespin @Lv.18 ➔ Shinnut @Lv.36 ➔ Chinken (Grass/Dark) - Chespin supposedly becomes more armoured with lengthened spikes, and becomes Defense orientated
Fennekin @Lv.18 ➔ Kinduples @Lv.36 ➔ Feuensis (Fire/Psychic) - Fennekin becomes bigger and has a necklace like thing of will-o’-wisps
Froakie @Lv.18 ➔ Ribburai @Lv.36 ➔ Crokssin (Water/Fighting) - Froakie remains slim and becomes like a ninja, it is a very fast Pokémon
Litleo @Lv. 15 ➔ Blazic (Fire/Poison) @Lv. 32 ➔ Mantiroar (Fire/Poison)
Helioptile @Lv. 35 ➔ Solaragon (Electric/Dragon)
Screeclaw @Lv.30 ➔ Whyrill @Lv.45 ➔ Noivern
Fletchling @Lv.14 ➔ Talonflame @Lv.30 ➔ Scorchawk
Swirlix (Moon Stone) ➔ Candilix (Fairy)
Spritzee (Moon Stone) ➔ Apothingo (Fairy/Flying)
Clauncher @Lv.28 ➔ Cannoclaw (Water/Electric)
Skrelp @Lv.28 ➔ Weeslep (Water/Poison)
There are supposedly 7 legendary Pokémon: Xerneas, Yveltal, a third cover Pokémon that looks like a snake with Poison/Rock typing, a Fairy-type trio based on spirits of natures (Fire/Fairy, Water/Fairy and Ground/Fairy), and a final odd-looking Pokémon. No details on event Pokémon
A minotaur with Fairy/Fighting typing with an incredible Attack stat, it is a psuedo-legendary.
A three stage dolphin line with Water/Psychic typing
A fire ant line that consists of three Pokémon, Bug/Fire
Another three stage line with Dark typing based on jaguars
Honedge is a standalone Pokémon
A nymph Pokémon
Mawile, Sableye, Farfetch’d, Dunsparce and Qwilfish all receive evolutions
Miltank, Taurus, Throh, Sawk and Audino all receive prevolutions
Mewtwo has two forms
Eevee receives a Poison-type evolution known as Toxeon
Orotto is Grass/Ghost type