The Hardhit Beetle is a boss in the Color Dungeon which was not in the original Link’s Awakening, but in the DX remaster for Game Boy Color, so he shows up for the Nintendo Switch remake too.
He’s not a terribly hard boss to defeat.
I do find it neat that he does change colors, as they made sure to make that a thing during the GBC days.
But with some skill.
He’s easily taken down.
Sadly he leaves no heart container or musical instrument.
But you get the choice of red mail or blue mail by the Great Fairy and her fountain. I chose the red tunic as it doubled my attack instead of the blue tunic which would of halved my damage. I did not regret my choice.