From the main menu select Battle Arena, then select Duel. Go into the Battle Options and change the CPU level to easy and rounds to 1. Then select P1 VS CPU. You can choose whatever Bakugan you like but put your opponent as one who is weak to yours. I used Maxus Dragonoid against Hades. Put your health to 150% when you're selecting your character with
and put your opponent's health to 50% with
when selecting it. The arena Interspace is the smallest so I suggest that.
Once the match starts you can do a physical combo such as
then just spam
, don't hold it down as you'll most likely miss. Matches should take about 20-30 seconds each. Just retry at the end and repeat until you have 30 wins.