There's really too much to consider that my head is blowing just thinking about this. On one hand you have all the advantages one type gets due to changes, then you have to consider the changes of every other single type and how abundance of use would be affected, and then whether the change in abundance would itself become an advantage, and then how this advantage would affect use, and then use back to advantage, it's like a cyclic system with random branches going out at random intervals that it's completely messing with me.
There's a point I made before about the random nature of competitive players' response being the key factor, and after considering that mindblow earlier, it's become especially prevalent that it would indeed be what most affects the changes in the Gen VI metagame. Because use and type advantages themselves are directly correlated, and that type advantages aren't subject to random audience interpretation, it is again all chance; who sets the trend, how influential a trend is, etc. I hate to mention this chance thing again because we are trying to reach something conclusive but fact is what in theory may seem completely correct in practice could be absolutely wrong. For example, i'm still convinced that most Fairies would probably only be defensive threats but no-one, including me would be surprised if that wasn't the case.
But despite this, i'll still make the attempt at prediction, after all, I guess the word "speculation" in the title of this thread makes up for everything I just blabbered on about. Heracross can be useful in countering the rise in steels, so I wouldn't discount him straight away, but that leads to a decrease in steels, which leads to a decease in fighting, which leads to an increase in steel and so that just brings us back to my previous point T_T
I noticed that many Fighting pokemon have access to Poison Jab so that in a way may provide some leverage against Fairies. A lot of them learn Bullet Punch as well, but that move isn't really threatening unless it's by Scizor.
We might be overlooking Fire's involvement in the change. Fairy -> Rise in Steel -> Rise in Fire -> Controls Fairy + Steel? Fire isn't known for its defence but being able to switch in safely on a Fairy and deal the offence it is reputed for would be excellent for wallbreaking and preventing a sweep.
I don't usually have any problems dealing with pursuit when using a Psychic, considering most of them learn focus blast anyway (yes, I know what you're going to say, a few learn aura sphere though). Latios is a bit of an exception, since I always run choice on it. *Opponent sends in Tyranitar* *Uses thunderbolt to do 15% dmg anyway*
Wouldn't having Ghost resist Fairies be a bit too much? Gengar would be all the more OP, it is infamous for being a glass cannon but i'm tipping that it would be able to survive a neutral fairy hit and 1HKO back with sludge bomb. That does stop fairies a bit, and maybe that's what you're getting at but then Gengar as an individual pokemon would be OP.
Ah, poison, it's funny i've never looked at them that way, defensively that is. Possibly because the likes of Gengar and Venusaur have overshadowed that thought. It's interesting to note that Toxicroak may have great use in the new metagame. It has one of the more damaging Poison Jabs and it has Sucker Punch to counter Psychics. What wouldn't surprise me though, is if they decided to give most Fairies access to the move Psychic, in which case Toxicroak will cry and heal itself with dry skin ? Maybe it's just me but when thinking Fairies I think magic, and Psychic is as magic as it gets.
Btw, the drama I was mentioning before was Journey to the West. It's funny that when you google translate fairy into Japanese, you get 妖精, but when you go Chinese, you get 仙女, and these two have almost opposite connotations associated with them.
Lol, I did not consider that when making the ball but here's a little clue for you: