SET-UP:
The first thing you need to do is make a Battle Deck. There are three ways to do this: 

The simplest method is to create 2 Battle Decks based on the white card that comes with the Starter Pack 
or 
Have each player bring their own "pre made" Battle Deck 
or 
Place all the Digimon cards face up on the table, and have each player pick their cards, taking turns after each card is chosen 

1. Each player selects a Rookie card and places it on the Duel Zone. 
2. Shuffle the remaining 29 cards and place them face down Online. 
3. Each player takes 10 cards off the top of Online for use as their own hand. 
 
 

1. Both players turn over their Rookies. 
2. Compare each player's Digimon Attack. 
3. Your attack is determined by the Battle Type of the opponent. 

Flip a coin to decide who goes first. 

The first player turns over a card on the Digivolve Zone and places it face up on the Duel Zone. Fulfill any requirements to complete your turn. 

The second player then decides to Digivolve his Digimon and fulfill the requirements, or says "pass" and moves their Digimon from the Digivolve Zone to Off line. 

DIGIVOLVE:
The primary way to win a duel is by Digivolving your Digimon. 

There are four levels of Digimon in Digi Battle. 
Rookie 
Champion 
Ultimate 
Mega 
The more you Digivolve your Digimon, the better your chances of winning the match. 

To find out if your Digimon can Digivolve, refer to the Digivolve requirements in the white box at the top of your card. 

If you see the name of the Digimon currently in the Duel Zone in the box, then there is a good chance that you can Digivolve. 

If the box says "off line 1 card" then you must take 1 card from Online and place it Off line when you Digivolve 

Wondering why someone would not want to Digivolve their Digimon? 

Sometimes, a lower level Digimon can be effective against a high level Digimon! 
For instance, What if your opponent Digivolves to Pukumon, a Mega. 
Before Digivolving your Rookie Agumon, you should check the Digimon Power of the cards. You could 
Digivolve to Togemon, but Togemon would have a very tough time trying to beat Pukumon. But if you look at your Rookie, Agumon can actually beat Pukumon all by himself. By not Digivolving you not only win, but you score a hefty 400 points too! 

BATTLE:
1. When both players have finished Digivolving, compare your battle types again.
2. The Digimon with the higher Digimon Power is currently winning the match. 
3. The player that went first in the Digivolve Phase goes first again. 
4. The first player may either pass (a good option if he/she is currently winning) or play a Power Option card. 
5. The second player may either play a Power Option card or pass. 
6. Both players may continue to play Power Option cards until both have passed. 
7. If one person stops playing Power Option cards, the other person may continue to play Power Option cards until he/she runs out. 
 
 

The number of points awarded to the winner of the duel is determined by the Digimon Level of the defeated card. For instance, if you beat an Ultimate, you are awarded the points listed next to "U" in the chart at the bottom of your card. 

The winner must Off line all Power Option cards. 

The loser must Off line all Power Option cards, and all Digimon in the Duel Zone, except for the Rookie card. 

REGROUP:
After battle, each player regroups by Off lining all or some of the cards in his/her hand. 

Both players then bring the total number of the cards in their hands to 10 by drawing them from the top of the Online Deck. 

Both players may place their higher level Digimon face down in the Digivolve Zone, if they wish to Digivolve. 
The loser may change Rookies if he/she wants. If the winner won the last duel with a Rookie, he/she may also change Rookies. 
To change Rookies, place the new Rookie face down on top of the old one. 
A Champion level Digimon can then be placed in the Digivolve Zone. 
Send the old Rookie Off line. 
Players now go to the Digivolve Phase and continue game 

ADDITIONAL INFO:
If at any time a player's Online deck runs out of cards, that player must Off line all cards on his/her side of the board except their Rookie. 

All the cards, except the Rookie, are then shuffled and placed face down on the Online deck. 

The game then resumes. 

Digivolving from Champion to Ultimate, or from Ultimate to Mega requires an Advanced Digivolve. 

For example, when Angemon is Digivolved to SkullMeramon, SkullMeramon needs a "Digivice" card to Digivolve. 

The Digivice must be the same color as the Battle type of SkullMeramon. 

The second Advanced Digivolve is the DNA Digivolve. 

To DNA Digivolve, you must play two lower level cards instead of one. 

FOR EXAMPLE:
To Digivolve to SaberLeomon (a Mega level Digimon) you must have Triceramon or Piximon in the Duel Zone, and SaberLeomon face down in the Digivolve Zone. 

Place SaberLeomon face up on the Duel Zone and place the needed Digimon (the one not already in the Duel Zone) face up on the Power Port.