Collect Rainbow Feathers dropped by Ho-Oh flying overhead, then befriend all three Legendary Beasts on their Dream Islands.

1. During clear or sunny weather, listen for Ho-Oh's cry and look up to spot it flying overhead.
2. Ho-Oh will drop a burning Rainbow Feather. Use a Water Gun move to put out the fire before picking it up.
3. Travel to the Dream Islands using Poké Dolls (Eevee, Pikachu, and Arcanine/Growlithe dolls) to find Suicune, Raikou, and Entei in their cave systems.
4. Interact with all three Legendary Beasts to complete their registry and unlock the Clear Bell recipe.
5. Craft the Clear Bell and ring it the next time Ho-Oh flies overhead to register it.