Ironsider

From the Super Mario Wiki

Ironsider breathing flames, along with two stone hands

Ironsider is the boss of Pecan Sands, whom Wario fought in Wario World. The fight takes place on a medium-sized, suspended arena with a sandy floor. Nine stone squares interrupt the sand.

This boss is a large, fire spurting, pulsing head made of solid iron, who enlists the help of huge stone hands in battle. Ironsider is impervious to Wario's punches, so the portly anti-hero must find some other way to damage it.

Ironsider has two attacks. The first sends out multiple shockwaves Wario's way, much like other bosses. Ironsider's second attack is a fire breath attack. The boss will sweep the entire area with the flame, making a roasting unavoidable. Even if Wario runs away, the flames move faster than Wario can run. The only way to avoid this attack is to Ground Pound and get stuck in the sand in the arena. The flames will then pass harmlessly overhead. Ironsider's hands cannot directly damage Wario. Instead, they opt to hold him in place to be punished by one of Ironsider's attacks. Shake the Control Stick to break free. Also, Ironsider's attacks will destroy the stone hands if they hit them.

The only way to hurt this boss is to beat up one of the hands, grab it and fling it at the metal monstrosity. Repeat five times to gain the right to fight Captain Skull.