Alolan Marowak w/Thick Club
Abilities: Rock Head or Cursed Body
Training (EVs): Max out attack, then go for defense and HP
Moveset: Flare Blitz/Fire Punch (STAB)
Shadow Bone (STAB)
Okay, first...let's go over the facts. Thick Club is a MUST. It DOUBLES Marowak's attack stat making him one of the hardest hitters in the game if not THE hardest hitter of all Pokemon including mythical and legendary Pokemon. I have used Marowak since Gen. 1 and strongly believe in his power.
Now, with that said, his weakness is his speed which is why you DO NOT invest any training points on his speed. Instead, work on his strengths. Attack, Defense, and HP for survival. Also, I, personally stay away from and trade away my lightning rod Marowaks. With Lightning Rod, when hit with an electric type move, it raises Marowak's special attack stat instead of doing damage. As an Adamant Marowak, the special attack stat means little to nothing. Instead, try for Rock Head which will prevent Marowak from sustaining recoil damage, therefore works best with Flare Blitz.
In addition, Flare Blitz also carries the Same Type Attack Bonus (STAB). If you cannot get a Rock Head Marowak, use a Cursed Body Marowak and switch out Flare Blitz and replace it with Fire Punch...that way you don't suffer the recoil damage from Flare Blitz. Let's move onto Shadow Bone...another STAB move capable of dealing massive damage. Then there is Bonemarang. Now, I know some of you are thinking, "why not Earthquake?" I answer: Earthquake is overused and in my opinion - overated. With Marowak's attack stat, Bonemarang (first hit) is enough to remove all substitutes, (second hit) then might be enough to KO on the way back. Yes, I'd gladly sacrifice 10 accuracy for that perk as opposed to the straight direct 1 hit earthquake that WILL fail to hurt the opposing Pokemon using moves like substitute. Yes, Bonemarang and Earthquake share the same base power. In the end, it's really your own preference. Moving on...I chose Smackdown as the last move. Seems crazy, right? Maybe even stupid? As a ground Pokemon, flying Pokemon seem all but untouchable; until Marowak and his high attack stack bring them right down to Earth. That [pretty weak] move tends to look pretty damn strong when Marowak's at the front of the helm utilizing it. In addition, it allows flying type Pokemon to be hit with ground type moves such as overrated Earthquake and preferred moves like Bonemarang. Trust me...as crazy as it sounds, it works.
Anyhow, this is my moveset with my Alolan Marowak. Feel free to try it out and let me know what you think.