looks like Dhelmise could be the mon you're looking for:
- Immunity to Fighting moves
- Resists Ground moves
- Steelworker giving STAB to Steel moves while also learning Anchor Shot fairly early (Level 32)
... But it's not in the game yet... so I'd recommend Deciudeye as an alternative. It shares the same typing but has less defense to take physical attacks (100 Base for Dhelmise vs 78 base for Owlboy) and lacks super effective moves for fairy types. On the bright side, Decidueye has access to Spirit Shackle which can also trap and let you deal with annoying mons while also having access to a recovery move (Synthesis) which Dhelmise lacks. Owlboy also learns U-turn ( which may you may need a heart scale for) and can form a Volt Switch/U-Turn core with your Heliolisk.
Or just get Crobat
Forgot to mention that Rowlet is available at Mossy Grove in Terajuma Jungle if the location guide is correct ( I don't know if it's an event or anything)