Invincibro

Invincibro is a glitch that allows the Fire Bro that normally remains inside the cave in the Wooded Kingdom to roam the map freely. Because the game does not expect this Fire Bro to be able to leave its designated area, some strange behavior occurs when it is able to access other areas of the map; notably, that it is invincible and cannot be killed by jumping on it.

Methods

There are two main methods that can be used to smuggle the Fire Bro out of its cave. One requires the use of two-player mode, while the other requires that World Peace is achieved in the Wooded Kingdom.

Glydon method

This method uses an out-of-bounds clip with Glydon in order to access the cave without activating the scarecrow. In order to use this method, Torkdrift must be defeated in order to attain the state of World Peace within the Wooded Kingdom, which is a prerequisite for Glydon to appear.

• After capturing Glydon at the top of the kingdom, fly to the Iron Road: Halfway Point checkpoint. There is a wall near this checkpoint that Glydon can clip through simply by jumping into it.
• Once Glydon has been clipped through the wall, immediately fly to the right and aim for the cave's interior. This allows Mario to not only bypass the scarecrow that is normally required to enter the cave, but also to take Glydon into it.
• After uncapturing Glydon, capture the Fire Bro and place it on the metal surface near the exit to the cave, facing toward the inside of the cave. If positioned here, it will already possess the invincibility property, since the player is not normally able to capture it to move it around.
• Capture Glydon and walk against the gate guarding the exit to the cave, then jump and immediately press the uncapture button. If done correctly, Mario should clip through the gate as he uncaptures Glydon.
• Activate the scarecrow to open the gate. At this point, the Fire Bro is already invincible, meaning Mario can simply bounce on it a few times to push it backward and out of the cave.