This is series 6 in Ranked Battles, Sword and Shield.
Primarina is a niche Pokemon with superfluous sp.def, allowing it tank one or two special attacks before falling, as well as being capable of dishing out humongous damage with its base 116 sp.atk. Additionally, Primarina is buffed in series 6 with the absence of Rillaboom. However, the question is, how do you stop this beast from going on a rampage?
Life orb, Liquid Voice Primarina can set up some serious damage. Due to the absence of Rillaboom, as well as the lack of viable electric and grass type mons in this series, the only possible counter for Primarina seems to be Dracozolt, who can hit for hustle + life orb Max Lightning. If a redirection from Amoongus happens, Primarina would Dazzling gleam/Moonblast + Dmax move into Dracozolt for the OHKO.
As far as I can see, I can't spot any efficient mons who can counter/check Primarina. Toxtrcitity seems good on paper. However, due to Primarina's superior special defense, it can't efficiently take it out, followed by max strike from hyper voice to deal enough damage to OHKO.
252+ SpA Life Orb Primarina Max Strike vs. 0 HP / 4 SpD Toxtricity: 136-161 (90.6 - 107.3%) -- 43.8% chance to OHKO
So my final question is:
How do you counter Primarina?
and:
How do you counter the counters for Primarina?