A Moon Ball has a 4x catch rate on Pokémon that evolve with a Moon Stone or belong to evolutionary families of the former.
The Moon Ball has an increased catch rate on:
Note: Some of these Pokémon cannot normally be found in the wild.
Crafting
To craft a Moon Ball, a Moon Ball Lid, a Button, and an Iron Base are needed.
To craft an Moon Ball Lid, one blue cooked Apricorn, one yellow cooked Apricorn and one black cooked Apricorn are needed. Placing the 3 cooked Apricorns in a row horizontally in a crafting bench, in that order, will produce two Moon Ball Discs, and then using the anvil will make them into Moon Ball Lids.