Mechawiggler

Mechawiggler is a boss encountered in nighttime Metro Kingdom, which is defeated to advance the kingdom to its daytime state. The fight consists of capturing a Sherm and firing bullets at its body segments when they stop and glow. There is additionally a rematch found in a castle tower on the east side of the Mushroom Kingdom.

The Mechawiggler fight in the Metro Kingdom can be skipped entirely using Morning Metro.

Gameplay

During the fight, Mechawiggler alternates between a vulnerable phase, in which it crawls along the walls of the arena and prepares projectiles that will begin moving toward Mario after a few seconds, and an invulnerable phase, during which it will emerge from the wall and charge along the ground at the player multiple times.

In the vulnerable phase, it will only become vulnerable a few seconds after starting the phase, which gives the player a good opportunity to begin removing some of its projectiles by shooting Sherm bullets at them. Once vulnerable, the player can begin attacking the body segments of the boss with Sherm bullets, which also deals splash damage to other nearby segments. Once all segments have been deactivated, the entire Mechawiggler will glow, and the player must shoot it six times to complete the hit.

Unlike most bosses in the game, Mechawiggler only requires two completed hits to defeat. However, if the player fails to deactivate all the segments within a certain timeframe, Mechawiggler will retreat back to its invulnerable phase. This prolongs the fight and can be a major time loss for speedrunners, but preserves the segments that were previously deactivated.

Metro Kingdom

The Metro Kingdom version of the fight begins with Mechawiggler in its vulnerable phase, except it only has nine segments and does not shoot projectiles as it does during subsequent phases. After its invulnerable phase, during which it will charge at Mario three times, it will resume a standard vulnerable phase in which it has 16 segments and prepares five projectiles to shoot at the player. If the player fails to deactivate all 16 segments before the Mechawiggler retreats, any subsequent invulnerable phases will only result in the boss charging at the player once.

Mushroom Kingdom

The Mushroom Kingdom rematch starts with Mechawiggler in its invulnerable phase, during which it will charge at the player twice. In this version, the Mechawiggler will split into two during invulnerable phases, with the two halves charging at Mario in an X-shaped pattern. During its vulnerable phases, it will have 15 segments, and it will prepare stronger pink projectiles that will each split into three standard projectiles after a few seconds if not destroyed; two during the first phase and five during the second, but it may sometimes stop to re-emit projectiles. After the player completes one successful hit on the boss, it will enter an invulnerable phase with three charges.

Patterns

In the Metro Kingdom version of the fight, speedrunners often struggle with anticipating the path Mechawiggler will take on the wall during the second vulnerable phase. Speedrunner Lupus has created a spreadsheet that documents all 22 possible paths the boss can take, each presumed to be equally likely. For each of the 11 possible starting points it can appear at on the wall, there are two different possible patterns, which can be distinguished from the direction Mechawiggler begins moving. In the spreadsheet, Lupus outlines mnemonics that can be used to memorize and recognize all 22 possible patterns.