https://www.smogon.com/dex/rs/pokemon/dustox/
[Overview]
With access to a phazing move, an immunity to Toxic, reliable recovery in Moonlight, and decent defenses to back it all up, Dustox has a lot of positive qualities for a Route 1 Bug. That said, its offenses are pitiful and its usable movepool is about as shallow as it gets, not to mention its typing means it has trouble walling a large portion of the special attackers in the tier that typically carry Fire- and Psychic-type coverage. Unless you absolutely need the positive aspects that its typing brings, most notably being practically immune to Fighting- and Grass-type attacks, you're probably better off choosing Wailord or Tropius for a phazer.
[SET]
name: Specially Defensive
move 1: Whirlwind
move 2: Moonlight
move 3: Toxic
move 4: Sludge Bomb / Hidden Power Bug
item: Leftovers
ability: Shield Dust
nature: Careful
evs: 252 HP / 4 Def / 252 SpD
[SET COMMENTS]
- Dustox can wall a few dangerous Pokemon and phaze them out for Spikes damage, notably Bellossom and Tangela, but also Roselia and other weak special attackers like Wailord
- Moonlight lets Dustox take on Hitmonchan and Huntail outside of rain throughout the match, and even outstall a few things like Sableye thanks to its immunity to Toxic
- Toxic is Dustox's best way of dealing damage outside of phazing for Spikes damage
- Sludge Bomb and HP Bug can be used for STAB, but they're horribly weak
[ADDITIONAL SET COMMENTS]
- More Defense can be run to better take on Hitmonchan's Earthquake, but it's largely a waste of EVs most of the time
- Hidden Power Fire can at least give Dustox an answer to Mawile outside Whirlwind, make sure to switch to Calm if doing so
- Light Screen can be used for further team support and can let Dustox take on Huntail and other things like Haunter better
- Necessitates Spikes support to make phazing worth it, as the only Calm Minder Dustox can really take on is Sableye
[Other Options]
- Psychic
- Thief
- Choice Band
[Checks and Counters]
- Golbat
- Flareon
- Mawile, Metang
- Relicanth
- Haunter
- Any decent physical attacker