The Moon Ball (Japanese: ムーンボールMoon Ball) is a type of Poké Ball introduced in Generation II. It can be used to catch a wild Pokémon, being more likely to succeed against Pokémon that evolve by using Moon Stone and their evolutionary relatives.
In Pokémon Gold, Silver, and Crystal, while it is intended to be more effective against Pokémon that evolve by using Moon Stone and their evolutionary relatives, due to a glitch it always has a 1× catch rate. (Instead, the Moon Ball is more effective against Pokémon that evolve by using a Burn Heal, but there are no such Pokémon.)
The Moon Ball cannot be used in situations in which Poké Balls cannot be used, such as in wild battles with two or more opponents currently present or against a trial Pokémon. If used in a Trainer battle, the opposing Trainer will bat the ball away, wasting the item.