As you unlock more and more characters on nintendo yugioh:the eternal duelist soul, to challenge against they get harder and harder and you'll have to change your deck around to sometimes specifically target a player, or just put in the new ones that are good right away.
Deck building can be frustrating at first because you want to try and build combos or themes to your decks but it's just not possible so you mainly have to just use your strongest monsters, the difference between a few attack points can mean victory and defeat a lot of the time.

Overall although I've been pretty critical about its downsides, the game is quite fun and it helps you understand what the heck is going on in the show because sometimes you just wonder.

Nintendo yugioh: the eternal duelist soul is excellent, it's like you are really playing some one. It is also very challenging!