Blaster Master Zero 3: Bloodstained Planade-G (No Sub-Weapons or Cross Wave)

Funnily enough this is probably the only boss in the entire game where not using the Cross Wave doesn't make much of a difference, thanks to it constantly changing its resistances and weaknesses in the second phase. As for the first, there's not much to say about it. A pretty forgettable "final boss" overall...so it's a good thing that, in typical BMZ fashion, there's still one more area to go through for the true ending.