Alolan Muk is also a fantastic choice, it's available really early on as a Shadow Grimer, it has an amazing stab combination, and it serves as an overall good special wall, also, it has great utility with Memento, Toxic and Screech to help with some harder battles. Another good choice is any pokemon with access to Tailwind, like Noivern or Whimsicott, it comes greatly appreciated. Lastly, i found Alolan Marowak wonderful for a beastly physical sweeper. You'll have to get a Thick club, though, but the benefits are incredible, that thing has great defense, and Ghost/Fire is a good stab combination. It can be found as early as the 4th gym, so you'll have an offensive juggernaut by the start of the game.
Oof, this got long, hope i helped
Yes, yes, yes, this thing is also good. You can do better if you get a Midnight form, thanks to Tough Claws, and priority in Accelerock