According to Pokéexperto, the Spanish version will see many attack and ability names that didn't quite fit be expanded thanks to the extra space added for attack moves in X and Y. In layman's terms, this means that if the same happens in the English version (currently unconfirmed, but likely), Thunderpunch will become Thunder Punch, Poisonpowder will become Poison Powder, and so on. However, what about Pokémon names that didn't quite fit, most notably Victreebel and Feraligatr? Pokéexperto suggests that they'll stay the same, because well, it's morally a bit harder to tamper with Pokémon names than with moves or abilities.
In somewhat related news, I got a hint of a rumor going around involving a list of Pokémon getting mega forms. This is almost definitely fake, for two reasons: it's missing Lucario, Blaziken and Mawile, and there's a mention of one of the Pokéexperto admins confirming Scizor getting one as well. However, a very quick look at Pokéexperto, their Twitter feed and the admin's personal Twitter reveals that no mention of Scizor whatsoever was made since the mega evolution mechanic reveal.
For kicks, here are the Pokémon that are in this list, excluding the ones that are already confirmed: Charizard, Blastoise, Gengar, Jynx, Pinsir, Gyarados, Aerodactyl, Scizor, Heracross, Houndoom, Tyranitar, Gardevoir, Medicham, Aggron, Banette, Latias, Latios and Abomasnow.
Interestingly, ANOTHER probably fake list has emerged, which omits Mewtwo, Absol, Mawile and Kangaskhan, which features six Pokémon from each region: all starters and three others, which are Gengar, Gyarados, Dragonite, Ampharos, Scizor, Tyranitar, Gardevoir, Milotic, Salamence, Staraptor, Garchomp, Lucario, Zoroark, Haxorus and Volcarona. What makes this one especially sketchy is that aside from the confirmed ones and the starters, these guys are almost all OU, to the exception of Staraptor (which is BL), Milotic and Zoroark (which are UU). (Not gonna get into Garchomp's tiering fiasco here, sorry.) Meanwhile, the ones that were omitted are either uber or waaaaaay down the tier list.
I usually don't comment on rumors, especially plain obvious fakes, but I just want to use the occasion to remind you to be wary.