In Pokémon Scarlet and Violet, you will need Leader's Crest to evolve Bisharp into its new evolution Kingambit. However, the rare Held Item is only obtainable with a hidden method that can be complicated if you don't know where to look for it.
Where to find Leader's Crest in Pokémon Scarlet & Violet?
Leader's Crest is one of the rarest Held Items in Paldea, as you can only find it in one spot on the entire Pokémon Scarlet and Violet map. You will also need to be decently far into the game before attempting to track the item down, as you have to catch a level 52 Pokémon to obtain it. Leader's Crest spawns in Fury Falls, a bamboo forest that sits above North Province (Area Two). The hidden valley is actually right next to Team Star's Fighting Crew base, so you can use the Starfall Street campaign marker to help find it. Once you have arrived at the serene forest, you will need to use the method explained below to find special Bisharp that carries the Leader's Crest item.
How to find a Bisharp with Leader's Crest in Pokémon Scarlet & Violet?
Leader's Crest can only be found on specific Bisharp who are surrounded by a group of Pawniard. No other Pokémon in the forest will drop it, and you can not obtain the Held Item any other way. So you will need to walk around the Bamboo valley until you see a Bisharp leader walking in a group. After you find the special Pokémon, engage it in battle and catch it. The Held Item will not drop if you knock it out, so you will need to add the Dark-type to your team. If you don't see any groups of Pawniard in the valley, simply run back and forth through the entire forest to reset the Pokémon spawns in the area. Once you've found and caught a Bisharp leader, it will automatically have Leader's Crest attached to its Held Item slot.
How to use Leader's Crest Held Item in Pokémon Scarlet & Violet
After obtaining it, you can find the Leader's Crest item in your Pokémon team roster by pressing the X button. Once the menu is pulled up, click the Bisharp you just caught with the A button and select the Change Held Item option to verify it has Leader's Crest. You can now equip the Held Item to any Pokémon that you choose. If you are trying to get the new Pokémon Scarlet and Violet Kingambit evolution, then just leave Leader's Crest attached to your Bisharp, and use it to knock out three more Bisharp group leaders in the forest to trigger its third evolutionary form.
For more information on Pokémon Scarlet and Violet, check out Where to find Eevee and its evolution stones here on Pro Game Guides.