You can literally make any Pokemon top tier ound ridiculous by mentioning how it deals with its checks and counters (see every C&C analysis for top tier Pokemon). I don't necessarily disagree that it can bypass these threats, but i'm confused as to why you tried to insult my intelligence by suggesting Alakazam as a potential check over acceptable checks like Choice Scarf Tyranitar or Azumarill. Pokemon isn't just a game of countering and checking; it's dynamic. There are times Yveltal isn't going to always work as intended. For example, you claim that nothing can switch into Yveltal but the reverse is also true. It simply won't have many opportunities to switch into other Pokemon (especially if Stealth Rock is up). On revenge kills, Yveltal itself is going to have difficulty forcing things out with that base speed stat, other than relying on that horribly telegraphed Sucker Punch. I'm seriously not sure how it can use Sucker Punch to completely mitigate it's speed stat. If you want a fully powered Sucker Punch, you need to use max attack, which makes all of its Special options weaker. The thing, it's movepool is mostly special, so you're going to have to split your EVs if you want to make good use of its special moves which lowers its offense. For gods sake, you're acting like Yveltal has access to all of it's sets at the same time. When you describe it i'm envisioning a set that consists of Sucker Punch, Dark Pulse, Oblivion Wing, Roost and Focus Blast, with maxed out evs.It can't steamroll Rotom-W if it invests in Attack (who's just going to switch in and burn you) and it can't deal with faster checks if it's Sucker Punch isn't fully powered up. Splitting EVs is perfectly permissible, but it just makes it that weaker on both sides. (Fun fact, non maxed Speed Yveltal is actually outspeed by Timid Rotom-W by a single point.)
By the way, it's only dealing 45~% to Terrakion with Sucker Punch at most; when I said that Terrakion was a check, I meant that it could always be counted on to revenge kill it/switch into a dark-type move, there's no need to mention that it's dying to Focus Blast or w/e, it's implicit knowledge. Keldeo doesn't need Choice Specs to beat Yveltal, it can absolutely murk it with just life orb alone (252 SpA Life Orb Keldeo Hydro Pump vs. 0 HP / 0- SpD : (73.53 - 86.76%) -- 87.5% chance to OHKO after Stealth Rock), and even non Life Orb Hydro Pump deals a significant amount of damage to if Stealth Rock is considered. Garchomp is absolutely a check, since it can force it out with Stone Edge or Outrage. Even Ice Shard users can deal with it if it's at a low enough percentage.
I'm not at all implying that's bad, but it's base 99 Speed is unquestionably mediocre in standard, and the existence of Stealth Rock makes its easy to pressure it. I'm absolutely positive that the standard metagame will change and adapt to accommodate Yveltal.
It's far too early to make any serious metagame assumptions about Sticky Web.
I was not trying to insult your intelligence by mentioning Alakazam and if it sounded like it I sincerely apologize, I should have been clearer on that. Didn't mean to offend you. :[
The set I was visualizing was the mixed set in the OP:
Yveltal @ Life Orb
Trait: Dark Aura
EVs: 252 SpA / 224 Speed / 32 Atk
Nature: Mild / Hasty
-Dark Pulse
-Oblivion Wing / Hurricane
-Sucker Punch
-Roost
(I don't see where I was trying to make it sound like it had five moveslots since it really only needs Focus Blast for one Pokemon - Tyranitar. I actually wasn't thinking about Focus Blast at all.)
The thing is, Yveltal doesn't need to split EVs for Sucker Punch at all - it already OHKOes a lot of faster would-be checks such as Thundurus and Jolteon (heck, freaking Garchomp takes 53% minimum from 0 Atk Yveltal holding Life Orb) - so it can run full investment for murderous special attacks. What Sucker Punch does do, however, is dramatically narrow the pool of possible things that
can be used as faster checks, so you don't feel the shortcomings of 99 Speed as much. At the end of the day, you're left with Scarf Tyranitar, Terrakion, LO/Specs Keldeo (I admit I forgot about LO, thanks for reminding me), Mamoswine, and Garchomp (again, this is what I am thinking of as of now) as things that can outspeed Yveltal and check it without dying horribly to Sucker Punch...but none of them can switch in well at all, all they can do is revenge kill. Garchomp is KOed by any attack followed by Sucker Punch, Keldeo is OHKOed by Yveltal's choice of Flying STAB, Mamoswine fails to OHKO with Ice Shard after SR and has a ton of HP for Yveltal to leech with Oblivion Wing, provided Mamo not below 60% HP where Sucker Punch kills. I will give you Scarf Tyranitar since I admittedly didn't think of it earlier. Terrakion is only a reliable switch if sandstorm is up. Without it, it can switch in and check Yveltal exactly once - Dark Pulse does 41% min, and if Rak takes more damage (lets say a layer of spikes is up) or tries to come in on another attack, it is in KO range of Sucker Punch. Is Terrakion a check to Yveltal? Definitely yes, and I wasn't trying to say it wasn't a check. Is it a good one? Sure...once. And it's not like Yveltal has to predict terribly well - these are literally just its STAB moves, both of which have amazing offensive coverage in Gen 6. Dark/Flying STAB coverage is soooo much better now since Steel lost its resistance to Dark.
Furthermore, Azumarill and Rotom-W are terrible answers to it. Azu is 2HKOed by Dark Pulse + Oblivion Wing (which heals off Aqua Jet damage maxing out at 41%) + Rocks, 252 HP Rotom-W takes 75% min from Dark Pulse and has no reliable recovery. The Specially Defensive set maxes at 48% with Volt Switch to 0 HP Yveltal which is pitiful and its slower, and Scarf can't come in at all. Being forced to run 252+ on Rotom-W without Scarf takes away from its other stats significantly just to check one Pokemon inadequately.
And you do have to admit that, yes, while SR is a pain to Yveltal, it's not as crippling to it as other mons. It has 126/95/98 defenses. It has Roost. One of its STAB moves drains 75% HP. It has ways to get around the rocks, despite its weakness. Yveltal also does have a fair few switch-in targets, for the record. Of particular note is its Ghost resistance, which is huge considering all the buffs ghosts have gotten this gen. Hippowdon, Zam, Latias, Latios (obviously not full power Draco Meteor), Celebi, Amoonguss, Venusaur, stuff like Jellicent, Gengar, Aegislash, Skarmory, Forretress, Ferrothorn, the Magic Bouncers, Sheer Force Landorus, pivot Landorus-T...Yveltal is not made of paper.
Basically all I am trying to say is that you are underestimating Yveltal significantly. I just think you shouldn't be so quick to treat it like another Kyurem(-B).
That's what Zygarde is for.