Hi, I have the game YuGiOh Dawn of destiny for my xbox and i have completed the game alredy. I was reading stuff on the internet about using your opponent's deck in single duel by holding down X at the single duel screen. It doesn't work. What Should I do?

the X thing only works in triple duel, not sure about single

Random Duelist is wrong. You cannot do it in Triple Duel's, but you can in Single Duels. the way you do it is Press X but keep it holded down then use the keypad to select who you want. once you have done that it will go back to the screen you were at before you pressed X. Choose your opponent and you will be using the person's deck you selected.

you have to beat all of the triple duels in triple duel mode. then you have to watch the credits all the way through, then you save it then you go into single duel mode and hold the x button to choose the deck you want to use then select your opponent. i know because i beat it with everything. it was tough.