Below I have posted the standard rules (what were officially called the "Digi-Battle Arena Rules")
Note: 2 sets of 30 card decks are required to play Arena rules.
1. Each player selects a ROOKIE card from the deck, and places it face down on the DUEL ZONE.
2. Each player shuffles the remaining 29 cards, deals himself or herself 10, and places the remaining 19 cards face down ONLINE.
3. Each player turns over the Rookie card in the Duel Zone.
Players now see which card their opponent has played and note its BATTLE TYPE: (RED CIRCLE), (GREEN SQUARE), or (YELLOW TRIANGLE). They then refer to the chart on their card showing the amount of DIGIMON POWER they can blast at that type of opponent. As you learn from playing STREET Dig-Battle, the player who displays the higher amount of Digimon Power has the advantage.
See example A.
The players now review the 10 cards in their hand and consider a strategy. To increase the amount of Digimon power you can blast at your opponent, you’ll probably want to Digivolve to the next level. Proceed to the DIGIVOLVE phase.
Example A. Ninjamon’s battle type is (GREEN SQUARE), and Clockmon’s battle type is (RED CIRCLE). That makes Ninjamon’s digimon power 320, and makes Clockmon’s digimon power 370.
Both players review their hands, and if they have a card that Digivolves their Digimon to the next level, they place it face down on the DIGIVOLVE ZONE. This new next-level card must show the name of the Digimon currently on the Duel Zone in its DIGIVOLVE REQUIREMENTS box, and you must be prepared to fulfill any other Digivlove Requirements stated there.
4. Flip a coin to decide who goes first.
5. Player who goes first turns over the card on the Digivolve Zone an places it face up on top of the card on the Duel Zone.
6. Player completes turn by fulfilling any Digivolve Requirements shown on the next-level card.
Digivolving from Rookie to Champion requires moving 1 2, or 3 cards from you hand to Offline as “payment.”
Digivolving from Champion to Ultimate or from Ultimate to Mega requires that you either:
a) Place a DIGIVICE Power Option* card on the POWER PORT, or
b) DNA Digivolve, which means you must play 2 lower-level cards instead of 1. You do this by placing the second Digimon (The one not showing on the Duel Zone) face up on the Power Port when you turn over the next-level Digimon on the Duel Zone.
*Note: There are three other Power Option cards that can be used in the Digivolve Phase. They are CONTROL SPRE, ULTRA DIGIVLVE, and DIGIVLOLVE TO CHAMPION. See instructions in the EFFECTS section of each card for use.
After the first player has finished Digivolving, the second player notes any changes in DIGIMON POWER, and may respond by either:
7. Digivolving as shown above, or
8. Deciding not to Digivolve and saying “Pass.” If the player who passes has a card face down on the Digivolve Zone, he must move it Offline, in other words, “Use it, or lose it.”
If a player does not have a card in hand to Digivolve, he or she must pass. If both players do not have cards in hand to Digivolve, proceed to BATTLE phase.
You may Digivolve only on level per Duel. After each player has either Digivolved or passed, the Digivolve phase is over. Proceed to BATTLE phase.
Starting with the winner of the coin toss, players now take turns playing POWER OPTION cards on the POWER PORT, one card per turn. Each Power Option card has an EFFECT that you can use to try for an advantage over your opponent. Some Power Option cards have Use Requirements attached to their Effect. You must complete these Use Requirements as part of you turn for the Effect to come into play. Keep track of how the dueling Digimon’s relative strength changes with each card played, as shown by comparing DIGIMON POWER.
Continue taking turns until a player runs out of Power Option cards to play, or decides to stop playing them, and says “Pass.” The other player may continue to play Power Option cards until he or she runs out of cards or decides to stop.
When the play stops, the player displaying the most Digimon Power wins the Duel.
Winner scores points depending on the Digivolve Level (Rookie, Champion, Ultimate, Mega) of the defeated opponent, as shown in the SCORE section at the bottom of the winning card. Winner adds the new points to his score counter.
Winner keeps all Digimon on the DUEL ZONE. Defeated player sends all Digimon, except Rookie, OFFLINE Both players send all Power Option cards Offline. (Unless a Power Option card specifically says to “keep this card on the power port”)
Winner goes first in the next Duel.
In the event of a tie, all Digimon remain on the Duel Zone and all Power Option cards are sent Offline. No points are scored. Winner of previous Duel (or of the coin toss) goes first in the next Duel.
The first player to score 1,000 points (or a lower number agreed upon bye the players before starting) wins the game.
First, you must restore you hand to 10 cards by drawing from the ONLINE deck. Players may discard as many cards from their remaining hand to OFFLINE as they wish, and draw as many new cards from the Online deck as they need to restore their hand to 10 cards. (This is the only time when you may restore your hand.)
When there are not enough cards remaining in the Online deck to restore you hand to 10 cards, draw down to zero, then send ALL the cards on you side of the board Offline. Shuffle them and place them face down Online. You may then draw as many as needed to restore your hand to 10 cards.
Note: If at any time during play the number of your Online deck goes down to zero (either by your action or you opponent’s), you must send ALL the cards on your side of the board, except the Rookie, Offline. Then shuffle them and place them face down Online before resuming play.
At this point, players have the option of changing their Rookie (if they have one showing on the Duel Zone). To set up a change, place the new Rookie face down on top of the old Rookie. (The old Rookie remains under the new Rookie.) If you have a Champion card with the Requirements to Digivolve your new Rookie to the next level, place it face down over both the new Rookie and the Champion in the Digivolve Zone, and you’ll send the old Rookie Offline.
Players may prepare to Digivolve any Digimon on their Duel Zone by placing the next-level card (with the correct Digivolve Requirements) face down on the Digivolve Zone.
Winner of the last Duel initiates the new Duel by starting at step #2 of B. DIGIVOLVE. (skipping step #1 of A. SET-UP) If the last Duel ended in a tie, the player who went first last time initiates the new Duel.