I dont know if I'm allowed to post since i'm not very experienced, but I think this analysis is overall correct.
Revenankh
How it is commonly used?
Revenankh's by far most used and effective set is the Bulk Up + Rest. It almost always consists of Bulk Up/Rest/Hammer Arm/Shadow Sneak and is usually paired with Shed Skin and Leftovers. Its two biggest selling points are its bulkiness and its ease to switch in. Shed Skin, in fact, grants him a virtual status immunity along with an heavily effective rest - whose length will be often cut off. These facts combined together make a lot of pokemon, which rely on statuses, simple setup fodder.
There are other sets, but the Bulk Up is the one with the most destructive potential. It can easily find room for many Bulk Ups and, once it has +6 to both Atk and Def, there are very few pokemon which can stop it, almost none which can revenge kill it. This is why almost any team must have a reliable and swift answer to Revenankh, much like Snorlax in the old G/S/C era.
Perhaps, the most important thing to remember is that its typing, ability and stats screw many common strategies. You cant Explode on it, since it is a Ghost. You cant rely on Toxic, Will-o-Wisp or Thunderwave - it will shrug off anything with Shed Skin and set up in your face. And, if it is not enough, the standard EV spread makes it so bulky that even supereffective special attacks cant 2HKO it if not backed by a good special attack stat. Revenankh is the reason why rely too boldly into pokemon like Blissey and Swampert has become a bigger liability than it used to be in the standard metagame
What else it can do?
Of the other options Revenankh can run, the most notably ones are the Choice, the Nasty Plot and the SubPunch sets. When equipped with a Choice Band, Revenankh packs quite a punch, and since it can easily force switches and almost none will dare switching in a Ghost, Focus Punch could hurt a lot. Similarly, the SubPunch set could give your opponent a hard time if it does not expect it and is unprepared. On the same wavelength, most special walls are scared off by Revenankh, so a Nasty Plot set could catch them offguard. Whichever set it runs, Revenankh can also be a nice spin blocker thanks to its Ghost typing.
Beware, however: these sets rely heavily on the surprise factor. Once the set is unveiled, these strategies lose most of their efficacy, and can be countered without much trouble - at least, when compared to the more threatening Bulk Up set.
Another tricky option, albeit not-so-common, is Ice Punch on the Bulk Up set. Most of its counters are hit supereffectively by this move (most notably Shaymin-S, Salamence and Zapdos), but the lack with either a Ghost or a Fighting move can open up for other kind of weaknesses, namely Azelf (Trick, Taunt and Specs Psychic which may OHKO with a modest nature), Gengar (Trick) and Alakazam (Trick, Encore and Specs Psychic which will almost always OHKO with a modest nature)
How do you stop it?
Skarmory fares pretty well against the standard Bulk Up Revenankh, thanks to its STABbed Brave Bird and Whirlwind, paired with a good enough defense to soak up Hammer Arm and Roost off the damage. Hyppowdon can also phaze the ghost and recover off the damage - Hammer Arm does not 2HKO even after a Bulk Up - but it cannot do much in return, as any residual damage/status from hazards can be erased by Rest. Similarly to Hippowdon, Fidgit and some other pokes can Encore its setup moves, but these methods will not kill him - at best they will force him out
Even if Revenankh is nigh impossible to OHKO with unboosted attacks, there are quite a few pokemon, like Shaymin-S, Celebi and Jirachi, which can 2HKO with the help of Choice Specs. However, Revenankh can hit them, switch out and heal off the damage later, while your revenge killers may not withstand repeated beatings - however annoyers like Subseed Shaymin-S and Leech Seed Celebi will create a lot of problems to the Ghost. Togekiss could work even without specs, but Hammer Arm will hurt a lot - especially when you think that, like Skarmory, Roosting in Rev's face means taking a supereffective hit from Hammer Arm.
Gyarados is almost always a good answer against Bulk Up Revenankh, since it can shut it down with Taunt and Dragon Dance without many second thoughts. Be careful, however, that since Revenankh has troubles with many Flying types but it can block Rapid Spin, Stealth Rock will be often up on the opponent's side, and so its Flying-typed pokemon like Gyarados, Shaymin-S and Salamence will all lose 25% right off the bat upon switching in.
Zapdos also makes a good counter, but needs a particular set. The common Roost/ThunderBolt/2nd attack/status or 3rd attack set loses to Revenankh since it does not deal enough damage. Rev will simply Bulk Up and Rest until it can smash you. The effective set Zapdos can run rely on the pair HP flying/Metal Sound. While its accuracy can be not perfect, Metal Sound is crucial to force Rev to switch. With its SP def cut in half, Hp flying is an easy 2HKO. However, depending on the other 2 moves Zapdos picks could have problem either with Gyarados or Scizor (Roost is hardly negotiable), since it will lack either Heat Wave or Thunderbolt.
If you want something more tailored rowards Revenankh, you need something which can nullify its main strengths. Taunt has already been noted, but Trick is even better, since, with a Choice Scarf equipped, Bulk Up Revenankh is pretty much useless. Beware of the rare choice variants, though. Another good idea, albeit gimmicky, is Worry Seed. With only one move it can negate the virtual status immunity granted by Shed Skin and prevent it from using Rest thanks to Insomnia. And, since not so many pokemon like to lose their ability, there are few safe switch ins even if you predict the Worry Seed.
Whichever way you choose to deal with Revenankh, be sure to have one on every CAP team you make and to put it into use swiftily. The more Bulk Ups Revenankh gets in, the fewer the possibilities to counter it will become. Needless to say, a fully setup Revenankh will rip your team apart. So, whichever thing you want to do, do it fast.
Hope it is good enough, otherwise feel free to edit or even delete it. And, BTW, I would give my credit to who used against me the Worry Seed + Toxic Torterra set, but onestly I dont remember who he was exactly - maybe Jagged_Angel or Deck Knight or anyone else, I cant remember now. As soon as I discover it I wll give my credit as due.
