Pokémon HeartGold and SoulSilver/Shiny Leaf

The Shining Leaf is an item found in HeartGold and SoulSilver. It is a very rare item that can be found by the player's Pokémon when walking around. When it is found by a Pokémon, it will have no apparent presence other than in that Pokémon's status screen. When a Shining Leaf is shown to the player's friend Lyra or Ethan, she/he will explain about them and request for the player to bring four more. When the player shows her/him a single Pokémon with five Shining Leaves attached to it, she/he will then award the player with star for his or her Trainer card, and then craft the leaves into a Leaf Crown.

A Pokémon can find a Shining Leaf while being in the grassy area of a route, but the specific route a certain Pokémon can find one depends solely on its nature. However, because of its rarity, a Pokémon is not guaranteed to find a Shining Leaf, even when the route and nature match. Therefore, the player should check their Pokémon frequently to make sure a Leaf can be found in that area. Whenever a Shining Leaf is found, upon examination, the Pokémon will have an exclamation mark above its head, do a dance swaying from right to left, then finish off with a green musical note above its head.

Locations
Following is a list of all the Shining Leaves found in the games, as well as the routes where they are found: