DeoSharp is one of the best HO cores in the metagame because of the offensive pressure it builds against the opposition.. Deoxys-D sets up hazards until it dies where the opponent will be under lots of pressure as switching is very common but now with SR + Spikes, your opponent will be taking lots of damage, especially if you consider Volt Switch and U-turn. Your opponent will either A: Rapid Spin with Excadrill (Gengar or Aegislash is commonly carried in this scenario) or B: Defog. If the opponent choose B, you can switch in on it and gain an instant +2 and possibly sweep your opponents team with ease. If you are ina favorable match-up, you can even get to +4! Thanks to the stacked boosts of and Adamant Nature, Life Orb / Dread Plate, Swords Dance, and STAB, Knock Off and Iron Head pretty much OHKO everything together. The steel-type nerf was a huge blessing; it now can destroy things like Scizor and Skarmory, things which ruined its viability. Sucker Punch makes it it impossible to revenge bar the rare Keldeo who takes massive damage from +2 LO Sucker Punch (+4 sometimes). In fact, Bisharp can set-up its own SD to sweep which makes Deoxys-D's hazards more efficient. Aegislash leading against Deoxys-D? Switch to Bisharp and decimate it with Knock Off (be careful of King's Shield though). This core is really good this generation and is standard and found commonly in upper level of play like SPL and OSL.
Yes, you can use Pursuit Aegislash and Bisharp. And yes, it's just as effective. The reason Tyranitar is often used with Mega Charizard Y is that it Pursuit trap everything that threatens Mega Charizard Y or can tank it like Latias, Talonflame, Raikou, Mega Charizard X, & Thundurus-I (assuming no Focus Blast / Superpower). Keldeo also forms a core with this too as Hydro Pump won't be hindered as sand is up v. sun. Sand and sun seem like a strange mix, but rememeber that Mega Charizard Y will get a full 5 new turns of sun when it comes back in which is nice. This core has been used a lot and for a good reason, it is the most powerful wall-breaking core along with Dual Birds. Another PKMN that fits good with this core is Lati@s as they provide necessary Defog support for Mega Charizard Y. Try it out yourself. It's called a "current metagame trend" for a reason.
There's a reason why Thundurus-I is almost always found with THE CRUMBLER. Thundurus-I is immune to Ground-type attacks and can threaten Mega Charizard Y which usually comes in on Aegislash, but the main reason is its ability, Prankster. Thunder Wave now has priority meaning that Aegislash will be able to nuke everything with Shadow Ball without having to take a hit. In addition to that, Aegislash's Pursuit traps Latias which is a hard stop to NP Thundurus. The two form a powerful S-Rank core able to destroy almost everything in sight. Thundurus-I also benefits with Aegislash's ability to beat Chansey which is often problematic. The core isn't something to built around alone as it's more of a supporting core for another core like KeldTar or ChompTar, so it's recommended to focus on its advantages in teambuilding instead of its offensive presence. It's still worth the hassle however and there's a reason it's found commonly: it is one of the best things to pair with Mega Charizard Y and Mega Tyranitar.
I wasn't a huge fan of Kyurem-B at any point of time because of its SR weakness and having to face its below-average speed. However, the resurgence of Zapdos and Defog has made it much more viable and with Zapdos no longer having to take boosted Hydro Pumps and Fire Blast in Gen V, it has become much more worthwhile. Toxic helps it where down lots of things for Kyurem-B to sweep from behind the Substitute. It can even tank Pixalate Hyper Voice from Sylveon and its longetivity is really good in the long run. It isn't as common as the aforementioned past 3 cores, but it has its merits.
Deoxys-S has managed to barely survive the suspect test meaning that OU can now use it again. With Deoxys-S finally staying, OU has discovered that the old Focus Sash lead isn't as effective compared to Deoxys-D leading us to a conclusion. Is Deoxys-S worth it? There are two sets, but please, Dual Screens isn't as good with Defog all over a place. Say hello to one of the best anti-metagame sets.
Deoxys-S | Life Orb | Pressure
Naive | 20 Atk / 236 SpA / 252 Spe
Psycho Boost | Ice Beam | Superpower | Stealth Rock
People often ignore how Deoxys-S has nice SpA. It's signature move Psycho Boost along with Ice Beam make it the best revenge-killer in the tier along with the ability to set up much needed Stealth Rock. Superpower is great as it lures in Tyranitar and OHKOes it. It even has usage against Heatran, Excadrill, and Greninja making it very valuable. The ability to revenge-kill, set up rocks, be a nice late-game cleaner, decent wall-breaker, and lure all in one set make it one of the best PKMN to use in OU.
These are common metagame trends that have been kick-started in usage after SPL. These cores are great and are used for a good reason. Other cores I did not mention were Landorus-I + Keldeo, Mega Tyranitar + Scizor, and Clefable + Suicune. Stall teams also have been great to use now with the metagame being much slower and a little kinder with Gen 6 being much bulkier. Zapdos + Kyurem-B isn't seen much, but I have seen it a couple times on the higher end of the ladder to a point where I am now introducing this to the public. Deoxys-S is really good. You should all give it a shot!
