On singles I use a Mega Salamence with jolly, evs invested in attack and speed. Dragon Claw, Protect, Double Edge and Earthquake.
A Jolly Kartana with a focus sash (because of the horrible sp def its normally a 1hko) Smart Strike, Sacred Sword, Night Slash and Leaf Blade. Usually if Salamence can't deal with it my Kartana finishes the job. The third slot I change constantly, but recently ive been using a Tapu Koko with expert belt.
On doubles I have Alolan Raichu and Tapu Koko because of the electric terrain combo. It's literally the same tapu koko I use on singles. Protect, Dazzling Gleam, Thunderbolt and Volt Switch in case i need to run from the field. Raichu is a physical raichu (really sucky for psychic but damn that volt tackle packs a punch). The other two pokemon I use are the Kartana and Salamence. I got to 50 on doubles with this setup. I haven't tried to go further, but the only real difficulties youll find are lightingrod pokemon and full ground teams for your first setup. Other pokemon I tried are unaware Pyukumuku with soak and toxic (Really bulky build with recover and substitute). If the toxic didnt work the soak would make it easier for tapu koko or raichu. Bewear with swords dance, hammer arm, double edge and earthquake is also a good choice. I have also a bruxish and palossand but they didn't really convince me that much.