To win the board game in the Game Room, keep in mind that the number showing on the die before it is rolled is the number that will show up if you count properly. For instance, if you would like to roll a "3", wait for "3" to show up on the top of the dice. Count six rotations before you strike the die and you will roll a "3".
If you use the Buster on the die (without locking target on the die), the number visible on top of the die before using Buster will always be set to the same number after punching the die into the air. Since you will only get the die rolling part with Nero, you do not have to worry about Dante.