So I encountered a build something like this while laddering and I was dumbfounded by it mostly because I was unprepared for it.
Deoxys-S (NOT A LEAD) @ Leftovers
Timid 252 HP/4 SpD/252 Spe
-Cosmic Power
-Recover
-Taunt
-Night Shade/Seismic Toss
I'm not sure about the EV spread. For all I know it ran Bold 252 Def/252 SpD. The point is that this set is quite brilliant in my opinion. It is designed as an incredibly fast staller that takes advantage of Deoxys-S' reasonable bulk, Pressure, and blistering speed and can be very hard to deal with if you're not prepared. It's also easy to function in a team. Its main weaknesses are Trick (which it almost always outspeeds and Taunts except for Scarfed Base 105s and above, which are rare), status (which I'll discuss later), the limitations of which attacking move it chooses (both are walled by one type), Taunters that are faster than it (there are none), and Trick Room (lol). Let's go over synergies on how to prevent these.
TrickChoice
Generally speaking, there's no 100% sure method to avoid Trick. My only advice is to use something that also uses a choice item, such as Jirachi, Kyogre, Garchomp, Scizor, etc. Ultimately though if you've been playing Gen IV for any amount of time you should know how to deal with Trick.
Attacking Move
Technically, you can run whatever you want, but the ones that I saw to be most effective were Seismic Toss and Night Shade. This is because they have reasonable coverage while doing a decent amount of damage to anyone besides Blissey, Wobbuffet, or Giratina forms. This set's bread and butter is the Cosmic Power+Recover tanking combo and Taunt is also needed for support, so you only really have room for one more move and it's a good idea to make it an attacking one incase you do somehow get taunted. Running Seismic Toss or Night Shade basically comes down to if you want to lose to Blissey or Giratina. Since G-O is used almost twice as much as Blissey, Night Shade is probably the better option. Blissey is also not very difficult to deal with since you can Taunt her and then switch out to something that can kill her. If she Ice Beams you can switch to Scizor or Jirachi, if she Seismic Tosses you can switch to Giratina-O, and no matter what she does you can switch to Dialga, Palkia, or Ho-oh.
Status
As with all walls who do not pack Rest, this guy is weak to status effects. As fas as status effects go though, this build is largely unaffected by Burn since Night Shade will do the same damage no matter what. Paralysis is an issue because it limits the ability to outspeed and Taunt things, but Thunder Wave users will usually be Taunted and Thunderhax is all luck which you can't really prepare for (aside from running Groudon I suppose). Sleep is also very minor since there are few things that can put this to sleep without being taunted first unless Darkrai decides not to get rid of his scarf. The biggest issue here is Toxic Spikes, which there are fortunately a number of ways to deal with.
Safeguard Wobbuffet - I say Wobbuffet because, even though practically everything in Ubers learns Safeguard, Wobbuffet is one of the best users of it. The strategy is simple here - Bring Wobb in on something Deoxys can come in on, Encore them to stall, set up a Safeguard, and then bring in Deoxys and stall.
Forretress - We ridin spinnaz. If anyone can find a way to make Starmie work in Ubers, that would be a good substitute too.
Lum Berry - Once you have +6 defenses, the leftovers recovery will be negligible. A simple way to have a catch-all for dealing with status is to forgo lefties entirely in favor of Lum.
Poison types that don't fly or have levitate so that they can absorb the TSpikes - Are you a bad enough dude to run Toxicroak in Ubers?
Taunters in your speed class (Other Deoxys-S)
They're almost all leads so you shouldn't have to worry too much about them. If you do encounter one, just switch out - you'll either win the speed tie and get hit by an attack, win the speed tie and successfully Taunt, or lose the speed tie, meaning that you have a 75% chance of not getting what you want.
Trick Room
lol who does that? Just run Scizor if you're really that worried.
So all in all I was impressed with this set.
Thoughts?
![Terywj [태리]](/data/avatars/l/71/71007.jpg?1555906021){kind=avatar}
