One Piece Card Game tournament play
Bandai runs organised play from store Treasure Cups and Regionals up to national and world championships.
Deck rules
Tournament decks follow the same rules as casual ones: one Leader, 50 cards in the Leader's colours, 4 copies maximum, 10 DON!!. Bandai publishes a ban and restriction list, which changes over time.
Formats and matches
Most events use the current Standard card pool. Store events are often single games; larger events usually play best of three in the top cut. Time limits depend on the event, so check the event page.
Conduct
Keep your DON!! and rested cards clear, announce attacks, Blockers and Counters out loud, and wait for your opponent to respond. Call a judge for disputes.