No rain, no flowers.
Salazzle @ Black Sludge
EVs: 252 HP / 4 SpD / 252 Spe
IVs: 0 Atk
This set excels at breaking defensive cores of types such as Poison, Water, and Steel for Poison-type teams. Thanks to Corrosion, Salazzle is able to cripple Pokemon such as Heatran, Celesteela, Toxapex, and Mega Venusaur with Toxic. Stalling for Toxic turns using Substitute and Protect also allows Salazzle to scout and find more opportunities to cripple opposing teams. Its above average Speed lets it stall out threats like Latios and Garchomp if Salazzle is behind a Substitute. Poison teams tend to struggle against Steel, as stallbreaker Heatran weakens the defensive core and opens the team to Pokemon such as Mega Scizor and Excadrill. Salazzle patches up this matchup by pressuring Steel teams when it can set up a Substitute by forcing a switch and cripple Heatran with Toxic. Once Heatran is out, Salazzle threatens the rest of Steel teams with Flamethrower. Nihilego is a good partner for this set, as it can not only provide Stealth Rock support but also take advantage of weakened defensive cores by cleaning late-game.
Here is a replay showing this Salazzle set in action!