When used from the Bag in a wild encounter, it attempts to catch the wild Pokémon. If the wild Pokémon is an Ultra Beast, it has a 5× catch rate modifier; otherwise, it has a 0.1× modifier.
Beast Balls 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.
Route 2 (during the UB Mission, if the player has no Beast Balls in their Bag) Route 8 (during the UB Mission, if the player has no Beast Balls in their Bag) Route 13 (during the UB Mission, if the player has no Beast Balls in their Bag) Seafolk Village (during the UB Mission, if the player has no Beast Balls in their Bag)
In Love at First Twirl!, Ash used almost every Beast Ball provided to the group to try and catch a Poipole in order to take care of it until the location of its Ultra Wormhole could be discovered. He eventually succeeded with the last one in the box.
In The Long Vault Home!, Ash, Lana, Kiawe, and Mallow each tried to catch a Stakataka with multiple Beast Balls, but it effortlessly dodged them all. Eventually, Ash was able to successfully catch Stakataka after getting rid of the statue that had been placed on top of its body and convincing it that they were going to return it to its home.
Lusamine first used a Beast Ball to catch the Naganadel that Phyco had earlier used to ride through Ultra Space. After riding the Naganadel to Ultra Megalopolis, she started throwing her Beast Balls at Necrozma in order to catch it. While her attention was focused on Necrozma, Sun used one of the Beast Balls that Lusamine had dropped to catch himself a Stakataka.
The Beast Ball, released in the Celestial Storm expansion, allows the player to look at their Prize cards. If an Ultra Beast is found, they may reveal it and add it to their hand, replacing the Prize card with Beast Ball.