Luminous Moss is an item in the “Held items” category (Items). It costs ₽4000.
In-game descriptions
| X / Y · Sun / Moon · Ultra Sun / Ultra Moon | An item to be held by a Pokémon. It boosts Sp. Def if hit with a Water-type attack. It can only be used once. |
|---|---|
| Let’s Go, Pikachu! / Let’s Go, Eevee! · Sword / Shield | An item to be held by a Pokémon. It boosts Sp. Def if the holder is hit with a Water-type attack. It can only be used once. |
Where to find it
Not placed on the atlas maps (so far: Red/Blue and Generation 3).
Sources : PokeAPI (items, item_flavor_text, machines) · atlas · pokeemerald species_info.h