Nanab Berry

A Nanab Berry is an item that will slow a Pokémon's movement, making it easier to capture on the Trainer's next attempt.

It is particularly useful on hovering Pokémon that move around randomly, such as Magnemite and Abra.

In-Game Description
Feed this to a Pokémon to calm it down, making it less erratic.

Trivia

 * In the original handheld series, Nanab Berries increase the cuteness of a Pokémon.