Sumo Bros's fire can be damaged/killed

[Void]

So I noticed that the fire produced by the Sumo Bros's lightning, amongst other projectile-type NPCs, can actually be harmed by specific NPCs. Bombs, Peach's Bombs, Shells, items being held by the player, and other similar objects the player can use offensively can actually damage and possibly even kill these NPCs. My main complaint is having to hear the boss damaged sound every single time this occurs. Maybe an NPC flag could be created that disables offensive NPCs from damaging them?

Oh, not only that, but immortal NPCs still can be hit by projectile-like NPCs. They don't lose health, but things like the boss hit sound effect still play.