While he looks like the leader of some weird rock band, Piers is the next to last gym leader in Pokemon Sword and Shield. I found him somewhat memorable.
He doesn’t really have a real gym trial, you basically just fight Team Yell members in dark alleys.
But the time comes to challenge him.
He uses dark Pokemon, which none of mine really had much effect against. And since you couldn’t use Dynamax transformations, I don’t recall having that difficult of a time defeating his squad.
After the battle, we find out that Piers is the older brother of Marnie.
Near the finale of the game, it’s heavily implied that he gave the title of gym leader to Marnie. How very sweet of him.