Collecting Power Chips is one way that your MUSHA can be powered up.

When a Power Chip Carrier appears, shoot at it until it drops Power Chips (up to four per carrier). Collect Power Chips to upgrade your Main Weapon. If you lose a MUSHA, your Main Weapon firepower will revert to its lowest level.

Option Weapons
For each three Power Chips collected, an Option Weapon is obtained. Up to two Option Weapons are equipped at a time, and remaining Option Weapons are put in stock. As you shoot, you will fire from both MUSHA and the Option Weapons. The Option Weapons can sustain several shots (when taking damage directly, instead of MUSHA) before being destroyed, but when one is lost a replacement from your stock will automatically be equipped. When you lose a MUSHA, the Option Weapon equipped will be lost as well, but those in stock will be retained. You can change the formation of the Option Weapons by pressing ( for the Classic Controller).