Zygarde Cube is an item in the “Gameplay” category (Key Items).
In-game descriptions
| Sun / Moon · Ultra Sun / Ultra Moon · Let’s Go, Pikachu! / Let’s Go, Eevee! | An item to store Zygarde Cores and Cells. You can also use it to teach Zygarde moves. |
|---|---|
| Sword / Shield | An item in which Zygarde Cores and Cells are gathered. You can also use it to change Zygarde’s forms. |
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