Pokemon with the Crush specialty are the shortcut for Copper Ore. Manual gathering works too, but a dedicated helper means you're never caught short. It goes into 1 recipe, so having a passive supply helps.

Smelt into copper ingots

Raw Material
MoveRock Smash Copper Ore Blocks
Rock Smash Rocky Ridges mines
Dream IslandRock Peak Dream Island
Requires: Give Drifloon a Clefairy Doll
LarvitarCrushDugtrioCrushPawmotCrushTyranitarCrushElectivireCrushCranidosCrushSteelixCrushGolemCrush
Copper Ore→Copper IngotSmelting Furnace

Copper Ingot is used in 5 crafting recipes

You can craft Bronze Wall, Cooking Pot and 3 more using Copper Ingot. These 5 recipes are mostly Utility and Blocks items that help fill out your island.

5 recipes
Bronze WallBlocks
Copper Ingotx2
Cooking PotUtility
Copper Ingotx2
Frying PanUtility
Copper Ingotx1
HandcarUtility
Copper Ingotx2
Striped WallBlocks
Copper Ingotx2

You can craft Scrap Cube using Copper Ore. These 1 recipes are mostly Blocks items that help fill out your island.

1 recipe