Since it has been brought up before, and I'm okay with it, how do you think X&Y will affect STABmons based on what we know so far?
1) Fairies -- The biggest game changer in a while is a brand-new type, but not just any type, one that hits super-effective against Dragons. Azumarill will get Water/Fairy/Normal, so if there is a reliable physical Fairy attack, it will have outstanding coverage in those three types.
Sylveon will get Normal/Fairy, and while we know hardly anything about the new evolution, it may prove to be just as potent as Espeon with access to Shell Smash.
2) Fire -- We have two new Fire-types to watch out for so far: Talonflame and Litleo. Talonflame will have Normal/Flying/Fire access, so a Shell Smash set with V-create may prove mighty powerful. Litleo, assuming it gets an evolution or has high stats, is also a contender since it too will have Normal/Fire, so if it's physically oriented, V-create spam might rise in usage.
3) Malamar -- I'm really excited about this one, not only because of its cool design and unique typing, but because it gets Contrary and Psycho Boost. If it can clear the way of other Darkmons, imagine it rampaging through the opponent's team with Scarfed Psycho Boost and a steadily increasing Special Attack...
4) Honedge -- Finally! Steel/Ghost. Will it be more defensive? Maybe it will sport a strong Attack? Either way, with a neat set of resistances, Honedge might be an answer to all the ESpeed spam. With No Guard, it will have a perfectly accurate Meteor Mash and Gear Grind to add with Shift Gear and any Ghost-moves like Shadow Force. If it learns Will-o-wisp, like most Ghosts, be prepared for it to shut down Kyurem-B as well.
5) Parabolic Charge -- Thanks to Helioptile, a new Electric move was introduced that heals the user of 1/2 the damage dealt, much like Giga Drain. Time will tell if it's Special or Physical and it's base power, but this may give some Electric-types like Magnezone, Thundurus, Electrivire, and Zapdos a new attack to their arsenal.