Just some quick information to look over and some people can add to if they would like. (Most may know this stuff but for those who do not)
In each pokemon game there is always a few changes here and there, Pokemon X/Y has brough more noticable changes and some more debated changes than any other game in the main series thus far... One of the bigest changes is the "Breeding" Process.
Will start with a few simple changes:
1. Hidden abilities have been slightly adjusted, as with several other things, in past games it was requiered for the mother to have the hidden ability. In X/Y the mother does not need to be the one with it for the trait to be past on. However... The stipulation with this is that you are breading with a ditto.
Basically if it is two of the same kind the mother still needs the hidden ability if it is a male with the ability it needs to be bred with a Ditto.
2. In X/Y the mother does determin the pokeball the offspring will appear in. So in other words if the mother is in a Cherish ball so will the offspring.
3. Egg moves also now seem to be able to be inherited from both the mother and father though it is not always a 100% chance.
4. If you have a parent holding a "Destiny Knot" when breeding 5IV's will be transfered to the offspring. (the 5 IV's are chosen from all 12, the 6 from both parents)
5. A parent holding an everstone while breeding will pass on it's nature to the offspring 100% of the time. so if you have a pokemon with nature you want put the everston on it before breeding.
6. Power items on a parent pokemon guarantee that spacific IV gets passed onto the offspring.
7. Having a pokemon in your party with "Flame Body" decresses the hatching time by half. Breeding items in debate:
Due to Game Freaks recent announcement of Shiny pokemon being more available once you have beaten the elite 4 and their increased appearance in the "Friends Safari" as well as the high availability of diferent region pokemon on the GTS/WT it has brough some debate into weather or not the Masuda method for breading a shiny pokemon is still viable in Pokemon X/Y.
Languages are also selectable at the stat of the game but the pokemon may be coded with regions they are from as well....
Further it has also been stated that "Tipping" also incresses the likelyhood of incountering shiny pokemon and is possible to incresse the likelyhood of breeding a shiny as well which if so may also lower the possibility of the Masuda method in this generation.
Due to Gamefreaks and Nintendos higher level of security on hacks neither have been known to be tested at this time.
Many do still believe the method is unchanged as there is no information from Game Freak either way at this time.
Also, GameFreak has hinted at something special happening if you acquier one of every pokemon in the game as a shiny version. Though have stated nothing beyond that.