At what area of ladder are you using this set exactly? Because anyone letting it get +2 with zero chip or status isnt very good. Max def primarina WILL beat it down with psynoise and draining kiss, not everyone uses assault vest.132 SpA Iron Moth Energy Ball vs. 252 HP / 252+ SpD Dondozo: 180-214 (35.7 - 42.4%) -- guaranteed 3HKO
132 SpA Iron Moth Sludge Wave vs. 252 HP / 252+ SpD Dondozo: 142-168 (28.1 - 33.3%) -- 0.1% chance to 3HKO
252 SpA Quark Drive Iron Moth Sludge Wave vs. 252 HP / 252+ SpD Dondozo: 201-237 (39.8 - 47%) -- guaranteed 3HKO
Even if its booster special attack, dozo can still take its hits alright. Only issue would be if its special attack booster+e-ball, which honestly, isn't the most uncommon thing, but not every moth is going to be it. A lot are speed booster, which dozo does fine against. A lot aren't energy ball and are either d-gleam or tera blast ground. And its job isn't to set curses on these special attackers, but to set up on weaker physical attackers (or even weaker special attackers) and then take one or two decently strong special attackers to contine sweeping.
Specially defensive can still take physical attackers on pretty fine, as after a curse or two, it takes so little damage. But it comes with the added benefit that it can take on a few special attackers briefly to contine sweeping.
252+ SpA Primarina Moonblast vs. 252 HP / 252+ SpD Dondozo: 157-186 (31.1 - 36.9%) -- 73% chance to 3HKO
252 SpA Iron Crown Psychic Noise vs. 252 HP / 252+ SpD Dondozo: 111-132 (22 - 26.1%) -- 7% chance to 4HKO
+2 0 Atk Dondozo Waterfall vs. 80 HP / 0 Def Primarina: 110-130 (34.2 - 40.4%) -- guaranteed 3HKO
+2 0 Atk Dondozo Waterfall vs. 0 HP / 0 Def Iron Crown: 172-204 (53.5 - 63.5%) -- guaranteed 2HKO
If primarina is even a bit chipped, then it doesn't beat dozo 1v1. Valiant is not switching in on it as it takes way too much from waterfall to be comfortable, while walking wake is mostly restricted to sun (heavy duty boots variants do like 45% max with draco).
Also waterfall does 35 to valiant? Unless you switch in on curse in which case you encore it immediately. I would love to see some replays of this in action, unaware Pokemon are notorious for farming low ladder but if you can pilot this against a competent player then by all means I'll concede.
At the end of the day you need to setup a curse on someone physical, these are the calcs you need to be concerned about:
252+ Atk Black Glasses Supreme Overlord 5 allies fainted Kingambit Kowtow Cleave vs. 252 HP / 4 Def Dondozo: 249-294 (49.4 - 58.3%) -- 98.8% chance to 2HKO
252 Atk Choice Band Zamazenta Close Combat vs. 252 HP / 4 Def Dondozo: 246-289 (48.8 - 57.3%) -- 92.6% chance to 2HKO
252 Atk Protosynthesis Great Tusk Headlong Rush vs. 252 HP / 4 Def Dondozo: 228-268 (45.2 - 53.1%) -- 31.6% chance to 2HKO
252 Atk Meowscarada Flower Trick vs. 252 HP / 4 Def Dondozo on a critical hit: 272-324 (53.9 - 64.2%) -- guaranteed 2HKO
240 Atk Soft Sand Landorus-Therian Earthquake vs. 252 HP / 4 Def Dondozo: 186-220 (36.9 - 43.6%) -- guaranteed 3HKO
Let's hope your dozo takes zero chip.