To add some more utility to the Metal Coat (it can only be used on Syther and Onix), it could also be sed to evolve the Pokemon that evolve via Magnetic Lure

Pokémon Go Lures, from Golden Lure to Rainy Lure, Glacial Lure

Wouldn't the iron sphere attract the treasure? : r/Tombofannihilation

How to get & use Metal Coat in Pokemon Go - Dexerto

Pokémon GO Special Evolutions – How To Get Pangoro, Sylveon, Glaceon, Aromatisse, Slurpuff, Sirfetch'd, Galarian Cofagrigus And More

How to get & use Metal Coat in Pokemon Go - Dexerto

Pokémon Go Winter Holiday Part 1 and Part 2, including Winter Wishes quest steps and best Choose Path choice

Pokémon Go Metal Coat - evolve Scyther into Scizor, Onix into

Pokemon Scarlet and Violet Metal Coat Location: How to evolve

Pokemon GO Metal Coat: How to Get, Use & More

What is Onix's evolution chart? - Quora

Shiny Steelix ( Onix Evolution ) Pokemon Trade Go

HOW TO EVOLVE ONIX INTO STEELIX IN POKEMON LEGENDS ARCEUS (HOW TO GET STEELIX)

Pokemon Brilliant Diamond & Shining Pearl: How to Evolve Onix into Steelix (Metal Coat Location)

How to evolve Onix into Steelix in Pokemon Brilliant Diamond