Heavy Fire Bro
From the Super Mario Wiki
Heavy Fire Bros. are enemies that first appear in Super Mario Maker 2, where they are exclusive to the Super Mario 3D World style. They are the Fire Bro equivalent of Sledge Bros., with red helmets and shells instead of green. They can be placed in courses by giving a regular Fire Bro a Super Mushroom. Heavy Fire Bros. attack by pounding the ground, stunning Mario if he is on the ground, and throwing fireballs.