Dustox

Shield Dust
Secondary effects won't occur.
Type Tier
Bug / Poison NU
Statistics
Min- Min Max Max+
HP
60
- 261 324 -
Atk
50
122 136 199 218
Def
70
158 176 239 262
SpA
50
122 136 199 218
SpD
90
194 216 279 306
Spe
65
149 166 229 251
Name Item Nature

Special Wall

Leftovers Careful
Moveset EVs
~ Light Screen
~ Moonlight
~ Whirlwind
~ Sludge Bomb
252 HP / 4 Atk / 252 SpD

Whirlwind's primary use is to stop the common Substitute Baton Passers from getting far with that. Sludge Bomb is used over other attacks for the power and 30% poison chance, but if you really want to be able to take on a specific Pokémon better, don't hesitate to change that. Light Screen and Moonlight absolutely shut down any special attacker you may see, except maybe Girafarig.

Name Item Nature

Physical Attacker

Choice Band Jolly / Adamant
Moveset EVs
~ Sludge Bomb
~ Aerial Ace
~ Hidden Power Ground
~ Sleep Talk
4 HP / 252 Atk / 252 Spe

STAB Sludge Bomb hits quite a few things hard in NU. Hidden Power Ground lets you hit Mawile and Sudowoodo for at least some damage. Aerial Ace and Hidden Power Ground already cover everything that resists Sludge Bomb, so another attack would be redundant. For this reason, Sleep Talk is probably your best option, so Dustox can absorb sleep moves.

Name Item Nature

SunnyBeamer

Leftovers Timid / Modest
Moveset EVs
~ Sunny Day
~ SolarBeam
~ Hidden Power Fire
~ Toxic
4 HP / 252 SpA / 252 Spe

The counters for this set are the exact opposite of the counters of the set above, so if the opponent expects a different set, you might be able to do something. Toxic is your only hope against things like Noctowl.

Other Options

You could use Silver Wind on a set for STAB, but it won't really be hitting much. Giga Drain can be used for Relicanth and the like.

EVs

Focus on your attacking stat for the two sweeper sets, with a bit of Speed. For the Special Wall, you'll want max HP, and a lot (maybe even max) Special Defense, with a Careful nature.

Opinion

Dustox is mostly inferior to other Pokémon if you use a sweeper set, thanks to its low Attack, but the Special Defense on this thing is good enough to stop most pure special sweepers. It should only be used on NU teams.

Counters

Sudowoodo, Relicanth, and anything else that carries a Rock attack will really put the hurt on Dustox, unless it's the SunnyBeamer, which somewhat sturdy Fliers like Noctowl and Pidgeot can wall with ease.