From Bulbapedia, the community-driven Pokémon encyclopedia.
Misty's special lure is a fishing lure created by Misty herself to help with her fishing for Template:Type2 Pokémon. It is a small model of herself in chibi style. She believes it to be the best in her collection of lures.
She has used it herself several times. It has gone under many redesigns, but all versions depict Misty in her original outfit.
She gave it to Ash as a gift in The Unbeatable Lightness of Seeing. He used it to fish for Buizel in Buizel Your Way out of This, and when Dawn asked to use it, he refused, leading to a short squabble between the two. Later in the episode, Buizel stole their rods, including Ash's with the lure attached; when they recovered them, Ash was glad to see the lure was still okay. As a result, this item has often been used as PokéShipping evidence.