Blaster Master Zero 3: Mantipede (No Sub-Weapons or Cross Wave)

The most fun fight in the game so far, it allows you to take advantage of all the upgrades you've gotten to this point. With its huge size allowing you to use the Rushing Attacker and its projectile attacks being reflectable by the Spinning Reflector, there's a variety of tactics you can use to take this boss out, and doing so is a blast.