Other than your deck be filled with just digimon cards there are also some support cards that you can consider adding and can change how you play the game in many ways.
same with digimon cards these support cards come in 7 colors and can be used in any color of decks.

The first support piece are option cards



option cards can be played on your turn and same with digimon has a play cost of how much memory is used to play that card.
Each option card is unique with a differetn skill and security skill.
If an option card is revealed in the security stack then it activates their security skill.
Most of the time it just activates what the card does or add the card to the hand, other times its something thats unique or it just doesn't have one.

Tamers



Tamers cards are vital in every deck. Not only do these cards provide the players multiple support they can change the outcome of the game and can be used in any deck. If they are shown in your security stack you can play them for free without paying the memory cost.

memory boosts



Memory boost cards, similar to option cards they have a special skill called delay which when sent to trashed gives you 2 memories

oh and Digi egg cards



Digiegg cards are not part of the main deck but are in whats known as the digiegg deck. You can only have have digiegg cards in that deck with 4 copies of a specific card.
they are preety essential to start any game off. they are the base of evolution for your digimon digivolving it into a level 3 - 7.