To start the battle, each player selects one Rookie-level Digimon card from their 30 card deck and places it face down in the Duel Zone. The players then shuffle the rest of their deck and draw 10 cards from it, placing the remaining cards in the Online Zone. Then, each player flips over their Digimon card.
If either player has a Digimon that Digivolves from their current Digimon, they place it face down on the Digivolve Zone. You can tell if a card Digivolves from a Digimon if the Digimon in the Duel Zone has its name inside the box below the new Digimon's level. Then, the players flip a coin to see who Digivolves first.
Whoever goes first starts by flipping over the card in the Digivolve Zone and places it on top of the card in the Duel Zone. The turn is finished by fulfilling any requirements that need to be fulfilled, such as sending cards from your hand to the Offline Zone, placing a Digivice in the Power Port, or even DNA Digivolving by placing the other Digimon detailed on the card on the Power Port.
After this player is done, the player going second has the option to either Digivolve their own Digimon, or, they can simply end their turn without Digivolving by moving the card in the Digivolve Zone, if any, to the Offline Zone.
Players who cannot Digivolve must pass, and if both players pass, than they proceed straight to the Battle Phase. In addition, each player can only Digivolve once per round, so whatever you Digivolve into you are stuck with until the next Digivolve Phase or until it is sent Offline.
Whoever won the coin flip in the Digivolve Phase starts the players off in playing Power Option cards on the Power Port, with each player alternating playing their Power Option cards. Every Power Option card has an effect to try and give you an edge over your opponent, such as power boosts or other effects. Some Power Option cards have requirements to use, similar to Digivolving. You must fulfill these requirements before the Power Option card will take effect.
Players continue to play Power Option cards until they run out or until one player passes.Then, the remaining player can continue playing Power Option cards until they run out or decide to finish.
Now players calculate how much power their Digimon has. Naturally, the Digimon with the most power wins. To start, each player identifies the color of their opponents Digimon, which is either red, green, or yellow, all shown in the box in the upper left corner of the card. Then, you match your opponent's type with the corresponding attack on your card, using the list of attacks and the colored symbol next to the attack. Next, you add up all of the Power Option effects to the players' Digimon, and finally apply any effects that would affect the power levels.
Whoever wins the fight scores points based on the levels of the defeated Digimon. A scale is on the card that will help determine how many points you get. Those points are then added to the winner's score counter. After the fight, all Power Option cards are sent Offline, unless it says otherwise, and the loser's Digimon cards, except for the Rookie are also sent Offline.
However, if there is a tie, no points are scored and both players keep their Digimon in the Duel Zone, although all Power Option cards are still sent Offline.
Whoever wins goes first in the next fight, and the players continue playing until on player has reached the agreed upon number of points (usually 1,000.)
First, both players return their hand to ten cards by drawing from their deck in the Online Zone. Players may also discard cards Offline in order to draw new ones as well. If there are no more cards left in the Online Deck, discard all of your cards on your side of the field Offline, except for your Rookie Digimon, and shuffle the pile, and place it face down in the Online Zone as your new deck, then draw the rest of your cards. This is done at any time your deck goes down to zero.
Next, both players have the option of changing their Rookie. To do this, players place a new Rookie face down over their current Digimon and send all cards underneath that Digimon's highest current evolution Offline. At this point, you begin the round at the Digivolve phase with either the winner of the last fight going first, or, if the fight ended in a tie, the person who went first last time goes first again.