(type chart)
http://www.pokemonxy.com/_ui/img/_en/art/Type-Matchup_chart_EN.pdf
Grass types are immune to powder and spore moves
Electric types cannot be afflicted with the Paralyzed condition
Ice types are immune to the Frozen condition
(Pokémon)
Mega Garchomp's Attack and Special Attack both improve greatly, while its Speed goes down a little.
Fur Coat is confirmed to half physical damage taken.
New move announced: "Furfrou can learn Baby-Doll Eyes", a Fairy-type move [...] the user goes first regardless of Speed [+1 priority I guess]. The move can lower the target's Attack stat.
Meowstick is confirmed to have different form and learnset depending on the gender.
Amaura's ability is called Refrigerate, with the effect we already knew: Normal-type moves become Ice-type moves.
Pyroark is confirmed to be Fire/Normal, with a different form depending on gender. His ability is Unnerve/Rivalry and he can learn Echoed Voice.
Everything else confirmed (Mewtwo X type/ability, fossils type/ability, etc.)
(more customization with the new pokemon)
"The stylish Pokémon Furfrou can have its appearance changed by grooming. There are number of different appearances it can take, and the more you groom it, the more styles may become available!
If you leave Furfrou's style untended for a few days, its fur will grow long and shaggy again, returning to its original look. Keep a regular grooming schedule to maintain Furfrou's style!"
(charachters)
Characther customization is confirmed: you can change outfit and hair style.
Also, there's this new thing:
http://www.pokemonxy.com/en-us/whats_new/pr_videos/
Team Flare is guided by 4 women with different hair style, and 1 man
New charachter revealed: "Diantha is a famous movie star beloved by everyone in the Kalos region. She's also a Pokémon Trainer who shows a lot of potential. She may even trade Pokémon with you sometime during your adventure!"