The Battle Experience system allowed Bakugan & Battle Gear to level-up in Bakugan Dimensions. Battle Experience gives you Gs on your Bakugan, Battle Gear, BakuNano, and/or Mobile Assaults that were used in battle. The higher the opponent's level, the more experience you'll get.
After every battle, a screen appears that tells you how many Gs your Bakugan have gained, and how many Experience points you have received from the battle. At the bottom, there is also a meter that tells you how many BakuCoins you have received from the battle.
It can also improve your Brains, Guts, and Spirit. Battle Experience also allows you to level up yourself, which allows you to equip stronger level Launchers/Gauntlets to boost your Guts, Brains, or Spirit.
Battle Gear gain more experience after battle and therefore, level up faster than Bakugan.
BakuNano are much like Battle Gear. They level up faster than Bakugan as well.