Baku-Gear Cards are a card type that is introduced in Bakugan: Armored Alliance, coinciding with the introduction of Baku-Gear. These cards function as Ability Cards, and are added to your deck, meaning only three copies are allowed per deck. To add a Baku-Gear Card to your deck, its Faction must match the Faction of at least one of the Bakugan in a player's deck.
To play a Baku-Gear Card, the player must first have enough uncharged Energy Cards to pay the Gear's Energy cost. To play a Baku-Gear Card, you place it underneath the Bakugan's Character Card you choose to play it on, so that the Baku-Gear's additional B-Power and Damage are visible at the bottom. You may choose to play a Baku-Gear on a Bakugan that does not match its Faction. Only one Baku-Gear Card can be added to a Character Card at a time, with the exception of Baku-Gear Cards marked with the Dual Baku-Gear effect. If this is not the case, then you must discard the existing Baku-Gear Card in order to replace it with a different one.