https://pokepast.es/3807c44530dcbb32
I chose sludge bomb in the last slot to hit Primarina because it's everywhere.
For the second team member, i chose Toxicroak because it has a nice synergy with Houndoom Dry skin allows it to freely switch into water types such as empoleon,tentacruel and suicune which would otherwise be problematic for houndoom.
Moreover, Toxicroak is solid against stall since it checks the blissey and alomomola core.
When facing Quagsire, substitute forces Quagsire to stay in and click earthquake.
Quagsire dies to a combination of focus punch plus a z-focus punch even rocks aren't on and leftovers weren't knocked.
Ice punch punishes gligar and latias on the switch safely.
However, the core brings 0 defensive utility and it especially weak to ground types.
Thus, i decided to follow up with some defensive mons.
Gligar not only offers ground immunity but alos volt switch immunity and acts as a solid defogger and checks Terrakion (which checks Houndoom),Zeraora,Cobalion and so on.
Defensive Primarina acts as a very solid hydreigon and infernape check which gives Houndoom a hard time to deal with.
It also serves as a check ground types such as Hippowdon and Swampert which this team could have a few ways to kill.
Next, i see myself still being weak to Latias, then scarf Scizor just popped into my mind.
It's fun and surprises opponents while being a great revenge killer against Latias,Celebi,Altaria and can sometimes even revenge kill fighting types like cobalion,Lucario due to it's surprise element.
Last but not least, i had Nihilego as a flying type check and my stealth rocker.
I opted for a life orb grass knot set to heavily damage annoying ground types.