Wow I've been keeping myself away from these "Top Tier" threads for awhile, simply because I've never seen any one of these be actually correct.
I don't see this thread being any different, this looks to be the most internet-fad oriented metagame that I've seen in awhile.
First off, Gyarados is decent, but it seems that people treat it as the most consistent deck to ever exist. It had a decent showing as far a some Battle Roads are concerned, but then again if 50% of the Pokemon community plays a deck it is bound to win sometimes... If you miss the Sableye start then the match switches from a 70-30 in Gyarados' favor to about a 20-80 in the other sides favor. The game has progressed, and we are far beyond the days of needing a starter Pokemon. Gyarados will remain a threat, but it has never been the threat it was presented as.
Secondly, Gliscor.dek is one of the worst cases of overhype I have ever seen. A good friend of mine referred to the deck as "an inconsistent Shuppet" and he is right. From the way that people are saying that they are going to play Gliscor, they think that they can get a good start every time, and keep Gliscor's coming consistently, when it seems almost ridiculous to even think of that as a possibility. Gliscor can deal 80 with Night Slash + Expert Belt, while Shuppet can normally get around 70 damage pretty quickly. The Poison/Paralyze may seem nice, but people are still able to Spray that (people think that Power Spray gets stopped by Spiritomb lolwut) not to mention that all it takes is a Stadium other than BTS or a Cyclone Energy to slow down Gliscor. The more people start to play the deck, the more those who created it laugh as they prepare their Kingdra's and thier Obamasnow's for cities.
Thirdly, you people are missing some serious things out there, just because you are blindsided by some of these decks. Things like Rhyperior (50+ Rage with 190HP) or Gengar Spiritomb. People are also missing things like Absol SW, which can be perfect for messing with Gliscor, Shuppet, and anything that uses Spiritomb to start. Ariados MT is another great card for this format, as it can destroy Spiritomb with Unown Q.