From the Super Mario Wiki
Floating Bandineros are a derived species of Bandineros in Wario Land: Shake It! On the ground, they serve the same purpose as regular Bandineros. However, they may inflate themselves to float in the sky, where they can obstruct Wario's path. Wario can send them to the ground by jumping on them, or he can defeat them by jumping at one after swinging on a pole. However, they can make themselves temporarily invincible by charging themselves with electricity. There is also a golden variety.