I've been making due with Flame Charge. It's alright, I guess. It gets Flare Blitz eventually, but Rock Head is a Hidden Ability, so its usefulness isn't great with Cursed Body. I wish I had Lightning Rod though, another immunity would be preferred because Marowak dies too easily to make use of Cursed Body.
I'm not really sure why Flame Wheel and Shadow Bone are before 28. There's no point. In fact, it learns Flame Wheel at two different levels before 28 (1 and 11)
Looking at its moveset makes me almost think it had a different evolution method (like Dusk Stone, maybe) before they settled on 28 at night late. A Marowak also doesn't change its stats in any way.
Shadow Bone looks like an excellent move... if Marowak could actually learn it without a Heart Scale. And without Thick Club, using A Marowak is basically pointless. It's bad. With Thick Club it turns into a glass cannon. A pretty decent one, if its movepool wasn't terrible. I was legitimately shocked they couldn't even allow it to learn the Shadow Claw TM.
Move distribution is wacky this game. Decidueye, a Pokemon partially based on Robin Hood, cannot learn Thief.