401.2. A registered decklist must have a complete, unambiguous record of the player's Champion Legend, battlefields, Main Deck including Chosen Champion, Rune Deck, and sideboard (if applicable to the format).
401.2.a. They must also include registered records of any cards selected for special additional deckbuilding rules. (Example: The three Legends selected for Neeko, Blending In must be registered on a player's decklist and can't be changed once they are submitted.)