What role would you give the Pokémon above in battle?

[Devalue]

Bulky attacker, preferably with Trick Room. Likely gives it Torch Song, Shadow Ball, Earth Power, and...Slack Off? Moves too slow to use Encore effectively (outside Trick Room). Never cared for Will-o-Wisp. Expects to benefit more from blowing something up or switching than reducing the enemy's Attack (in Skeledirge's case). Could pick Heat Wave, Snarl, or Protect over Slack Off in a Doubles situation. Leans away from Fire Pledge, despite the uniqueness of actually combining it with another Pledge move.

Lycanroc (Midnight)?

 

[Sweet Serenity]

Physical wallbreaker.

It's not really that fast enough to sweep with 82 Speed, but its 115 Attack makes it hit decently hard. Give it a Choice Band and Accelerock and I can take down some good defenses.

Magnezone?

 

[CabaiaJ]

Bulky Special Attacker. I don't think I've ever used it as anything else. It's got solid base special attack at 130. Its HP leaves a bit to be desired, but it has respectable defense and special defense at 115 and 90, so it can take a few hits while dealing a lot of damage back. Also, the ability to trap other bulky steel types often proves quite helpful for your overall team. In the past, I tended to drop a Specs on it most of the time, but it could benefit from an Air Balloon or even something more niche like a Red Card to possibly draw in the steel types that the opponent didn't want to bring in.

Let's go with one that I've used in many different ways:

Scizor?

 

[Sweet Serenity]

Wallbreaker, especially after setting up with Swords Dance. With Technician, Swords Dance, and priority Bullet Punch, it's really good. I used Scizor quite often during gen 8 and it never disappointed.

Poliwrath?