As long it doesn't have a good custom movepool for coverage like Alcreamie did, Steelix or Stunfisk (Galar Form), despite their poor speed, make excellent options.
Remember to give them Stomping Tantrum over Earthquake so allies don't get hurt.
Just battled a G-Max Toxtricity for the first time. It was only a 3* Raid, so Dugtrio took care of it with ease. Broke out of the Poké Ball after three rumbles though, hopefully I'll still be able to catch one.