First things first, even though this account is not new, thanks for the welcome.
Blue is technically plasma, not fire, and maybe they mistook orange fire with yellow fire?
Anyway, I keep asking what kind of armor Galleom has that can be agreed by everyone because if Galleom has Chobham (tank) armor or anything similar, which is heat resistant and can take almost all physical blows, then fire would be useless...as would most physical, non-metal piercing attacks.
Then again, Giga Bowser has big scales and a very tough shell, but I doubt they are as tough as reinforced, multi-layered armor.