Evolved Bakugan
Here's how you unlock the evolved Bakugan forms.
First, you must beat the character in the park to unlock the un-evolved form of their Bakugan.
After unlocking their un-evolved Bakugan purchase it at the shop.
Once you have beaten the game, challenge that character again.
Upon winning you will have unlocked the evolved form of their Bakugan in the shop.
For example, to unlock Delta Dragonoid II:
Beat Dan at the park unlocking Dragonoid.
Purchase Dragonoid.
Challenge Dan in the park after beating the game.
After beating Dan Delta Dragonoid II will be in the shop available for purchase.
Notes
You DO NOT have to beat the players with their own element.
You DO NOT have to beat the players in a specific battle type.(1v1, Battle Royal, Tag Team).
You MUST battle the player when their difficulty is set to "HARD."
You DO NOT have to actually beat their Bakugan in the battle to unlock it (you could get 3 double stands and still unlock their Bakugan).
Various codes
Enter one of the following codes as your name at the start of a new game to activate the corresponding cheat function.
1,000 BP - Enter 33204429 as a code.
5,000 BP - Enter 42348294 as a code.
10,000 BP - Enter 46836478 as a code.
100,000 BP - Enter 18499753 as a code.
500,000 BP - Enter 26037947 as a code.
Bronze Warius - Enter 44982493 as a code.