My own personal opinion on the state of Defog of NU (feel free to disagree):
After giving every single new defogger in USUM a somewhat fair chance (at least I'd say, I tried each one at least 5 times with a dedicated team around them with like the exception of bad silvally forms and ghost rotom), my results have been:
-Silvally's are garbage (someone make this work and prove me wrong) because they:
1) have no reliable recovery nor leftovers not amazing enough bulk (95/95 is decent don't get me wrong) to offset the first two downsides (T-spikes = gg because Silvally-Poison literally loses to every rocker)
2) do not have a catch-all typing against every hazard setter in the tier as well as anti-hazard deterrents
Examples include: (probably best one but kinda ass) Water losing Toxic Seismitoad and Garbodor, Dragon losing to Piloswine, Sneasel and more offensive Druddigon builds and still Garbodor, and Steel losing to Steelix and Rhydon. (All the other forms are considerably worse having tried Fairy/Fighting/Electric/Ground)
3) Kind of 4mss as well. Parting Shot/Surf/Toxic/Defog "hits" the most, but will let Vileplume in so free among other things that escape my brain atm. T-wave replacing toxic removes any chance of beating Seismitoad, Ice Beam instead of Surf WILL make you lose vs Rhydon/Lix, and anything replacing parting shot removes its biggest niche imo.
-Sigilyph is a mixed bag. All in all, NOT a Xatu [REPLACEMENT] but not bad depending on team build.
two sets: defensive and offensive defog but both come with a decent amount of crippling weaknesses
1) Both suffer heavily and I do mean HEAVILY of 4mss.
-In offensive sets, every combo of Energy Ball, Psychic, Heat Wave, Dazzling Gleam, Air Slash, Dark Pulse, and Roost will leave you walled by at least something. I personally like going 3 atks, Energy Ball, Dazzling Gleam, Psychic (walled by Delphox, Incineroar) but in the end, still walled by just too many things (not to mention, only modest energy ball kills most full health Rhydons) and will have to sacrifice Roost which is much appreciated in anything not HO. Tinted Lens is alright (2 atks Roost) but taking SR as a defogger and losing out on Life Orb recoil immunity is ew.
2) Defensive sets people have been talking about, oh lord. King of 4mss. Psycho Shift Flame Orb pretty much gives you one attack, which most of the time is like Air Slash or Psychic so either: one weak STAB, or not being able to do anything to darks except burn them. Either way, CM Delphox/NP Houndoom especially has a field day against these sets as well as still being rekt by Sneasel which some Xatu's can play around by unning protect to scout or just u-turn in prediction. Also you either kind of have to pick either getting outsped alot or taking way more than you want to by attacks.
-Defog Whimsicott is more like a "light hazard control" option as you really can't depend on fogging all game due to astronomically low bulk but more offensive teams that can free the Encore/Memento/Tailwind slot, this is a decent option.
-Defog Mowtom is kind of in the same boat, splashing defog on the 4th slot is probably the best option (Defog on choice sets aren't that bad). I've ran a defensive Calm nature set w/ leftovers with VS/LS/WoW or PS/Defog but it's rather "eh" as it lacks firepower and doesn't have an amazing defensive typing as well as deciding between Wisp and Split is very difficult considering you want to crippling physical set up sweepers or actually have some form of real recovery.
-Drampa is simply unfit for the role as it much rather be clicking Draco and Noctowl is still lol even w/ flyinium z tinted lens.
I want to give attention to I'd argue is the current GOAT at defog:
Altaria @ Leftovers
Ability: Natural Cure
EVs: 248 HP / 160 Def / 100 SpD
Bold Nature
IVs: 0 Atk
- Roost
- Defog
- Toxic
- Flamethrower
(Spread lives any attack besides Head Smash from CB Emboar and Altaria doesn't NEED to outspeed anything so spdef investment helps a lot also customize your own spread if you don't like it bub)
Ok, I know this is a passive shit, but damn if this wasn't the GOAT.
+walls Delphox, AV Hariyama, both Rotoms, Emboar (no head smash uprising pls), Accelgor, Swords dance Rott, Scyther, Defensive Garbodors, and Steelix (a bunch of other shit like ScarfDoom, non-stone edge Virizion, and Hitmonlee just too much to list)
+Wins any and every status spam war due to Natural Cure aka middle finger to Toxic Seismitoad, Toxic/Glare Druddigon, Toxic/Wave Miltank,
Wish Toxic Tect Delphox
-However will take a back pedal on things like Shed Skin Scrafty (bad), Guts Hariyama, Cryogonal, and Mesprit coverage.
(ok I'm lazy so the rest of this research paper is bad and I have to do things other than write for digimons)
Good teammates include ice resists AV yama and shit. No replays but here's calcs.
252 SpA Delphox Dazzling Gleam vs. 248 HP / 100 SpD Altaria: 140-166 (39.6 - 47%) -- guaranteed 3HKO after Leftovers recovery
252+ Atk Choice Band Reckless Emboar Wild Charge vs. 248 HP / 160+ Def Altaria: 157-185 (44.4 - 52.4%) -- guaranteed 3HKO after Leftovers recovery
252+ Atk Hariyama Knock Off (97.5 BP) vs. 248 HP / 160+ Def Altaria: 92-109 (26 - 30.8%) -- 4.3% chance to 4HKO after Leftovers recovery
252+ Atk Steelix Heavy Slam (120 BP) vs. 248 HP / 160+ Def Altaria: 135-160 (38.2 - 45.3%) -- guaranteed 3HKO after Leftovers recovery