Reserving Dusknoir for 1v1. He is not on the VR. Here is my analysis to show why he deserves to be.
[SET]
name: Frisk Disable
move 1: Disable
move 2: Poltergeist
move 3: Shadow Sneak
move 4: Taunt/Earthquake
item: Kasib Berry/Spell Tag
ability: Frisk
nature: Adamant
evs: 252 HP / 252 Atk / 4 Spe
[SET COMMENTS]
The main purpose of this Dusknoir, where he will get the most wins, is against enemy Choice users. With Frisk, you can guarantee that they are using a Choice item. With Dusknoir's bulk, you most likely will survive a hit. Simply press Disable and usually Poltergeist+Shadow Sneak to defeat most Choice users. Dusknoir can also beat many non-Choice users if they lack the power to deal >50% damage to him, with 2 Poltergeists and a Shadow Sneak, as well as many stall Pokemon with Taunt+Disable. Do not pick Dusknoir against very strong Choice users such as Dracovish which can OHKO this set. Against a low Defense high Attack choice user like Darmanitan-Galar, use Poltergeist+Shadow Sneak instead of Disable, as you will be 2HKO before you can KO them back, while just attacking has a good chance to get you the win.
Kasib Berry enables you to beat Alolan Marowak and Dragapult, but could be swapped for Spell Tag if your team covers those two well.
Earthquake gives you a move that hits Normal types, and gives you a move to use in case the opponent uses something like Power Herb which causes Poltergeist to fail. Note that a Super Effective Earthquake has roughly the same power as a Poltergeist with a Spell Tag boost, so Taunt is generally preferred as it improves more matchups.