Food, The Way to a Duelist's Heart
The standard way to acquire a new tag team partner for dueling is to battle and defeat that character in a one-on-one match. However, defeating a difficult opponent is easier said than done. To get partners an easier way, start by going to a store. Buy as many sandwiches as you can before you run out of room to store them. Walk up to the duelist that you want to recruit and give them the sandwiches. The duelist's Hearts will increase and they will be happy to duel with you.
Win Without Winning
Challenge anybody to a duel and add the final countdown card to your deck. Activate your Final Countdown card. All you have to do now is survive for 20 turns to win the duel without actually beating your opponent. You also earn 1,000 Duel Points for winning this way.
Free Card
You will meet a student named Blair during the game. When you do, challenge him to a duel immediately. The battle takes place at the harbor at night time. Defeat Blair and you will receive the Hero Emerges card, a valuable card that can be used to summon high level monsters.
Help Dorothy
Miss Dorothy will approach you for help on one of the exam days. She will be struggling to deliver her card packs and will require your assistance. This is not exactly the most exiting proposition and you will probably refuse, but lending a hand has a major benefit: Miss Dorothy gives you a free card pack to show her appreciation. The same card pack becomes available later in the game but will cost you 1,000 Duel Points.
Become Alexis' Friend
If your rank is either Dropout Boy or Duel Apprentice, head to the girl's dorm at nighttime when Alexis is around. Save the game just before you enter the dorm. Duel Alexis and her two friends and beat them all to become friends with Alexis. You only get one chance at this duel, so reload your saved game if you fail, to wipe your game's memory of the fight and try it again.