Waterwraith

The Waterwraith is a boss from  and, found in all sublevels of the Submerged Castle and Engulfed Castle, respectively.

It can only be damaged by Purple Pikmin's stomps, which are implied to emit gravitational waves in Pikmin 4; however, the entrances to both the Submerged Castle and the Engulfed Castle are flooded, making them impossible to bring along. Since Purple Pikmin are only obtainable in both cave's final floors, the Waterwraith is completely invincible and immune to attacks in the first four sublevels.

The Waterwraith is one of the few bosses introduced prior to Pikmin 4 that has its own unique background music, along with the Giant Breadbug and Vehemoth Phosbat. In the Submerged Castle, when it appears, as detailed here and here.

Behavior
The Waterwraith is one of the most dangerous enemies, as it can instantly kill Pikmin by just rolling over them, and cannot be deterred or defeated without Purple Pikmin. When it appears, its rollers drop from the sky first, and then the creature proper, latching on to the rollers with its limbs. After a roar where it lifts the front roller and then slams it, it shakes itself to get ready to roll. Throughout its time active, it strolls around the cave floor, partially aiming at the player and their Pikmin, partially roaming around at random.

If a Purple Pikmin slams nearby, it becomes tangible and cowers in fear. After a while it will return to its intangible form, slam the front roller again, and continue moving. When its rollers are destroyed, it runs around the area on its legs, sometimes stopping to catch its breath, and if the player is far enough away, it will walk around at a leisurely pace. When attacked by Pikmin, it will eventually either shake them off or start running away. When the creature is finally dead, it starts bursting into chunks which fizzle in the air until the beast disappears entirely.

After taking out the Waterwraith's rollers and entering the second stage of the fight, if the player is sufficiently far away from the boss, it will stop walking randomly and will instead stand in place. In this animation (see right), it also occasionally turns around back and forth. This elusive animation can only be seen by being far enough away, by using the zoomed-out or ground-level camera settings, and by being on sublevel 5 of the Submerged Castle, since it is too dark to see that far away on the Bully Den. This animation can be better seen in the Piklopedia in Pikmin 4, where the rollers can actually be destroyed.

In Cavern for a King, if a Waterwraith with its rollers approaches one without, the rollerless Wraith will duck to let the other one over.

Unconventional damage
Typically, the Waterwraith cannot be hurt at all except for when a Purple Pikmin lands near it. There are however ways to cause it to become vulnerable, hurt, or even killed, but they require some setup and luck, and are likely not intended methods of damaging the beast.

In Pikmin 2, if a Waterwraith lands on top of a treasure, it will look like it's bouncing in the air. In some rare cases, it may slam onto the ground as it lands, possibly triggering its vulnerable status, making it possible to damage it before floor 5.

In Pikmin 4, it can be frozen with an ice blast or Ice Pikmin, and can be stunned with a lightning shock, but it will break free almost instantly. The player can however make use of the fact that frozen enemies instantly lose all their health if they are mid-air and fall. With careful positioning and timing, the player can prepare a mine and an ice blast, then throw another ice blast while directly in front of the creature as Oatchi. This will cause the Waterwraith to instantly freeze, and since it just started running over Oatchi's mine, it will be slightly airborne. The fall will make it lose all its health, meaning its rollers will be destroyed. After this it jolts backwards and if it lands on top of the mine and the first ice blast freezes it, it may again fall off the mine and instantly die.

Appearance
Its appearance is generally humanoid in shape, with the suggestion of a head, body, arms, and legs, but without distinct characteristics, and with a watery, transparent body. As a matter of fact, its scientific name is Amphibio sapiens, which is similar to the human's scientific name: Homo sapiens. When hit with Purple Pikmin, it instead changes to a solid, somewhat shiny purple color. Its rollers are cylinders made of stone, with small holes on the sides for the Waterwraith's limbs to go into. These holes are in the center, except for the back roller's holes in Pikmin 4, which were positioned closer to the rims. This is because in both games, the Waterwraith moves its legs around the roller to make it look like it's pedaling a bicycle.

The Hocotate ship notes that although it can be seen, its sensors somehow detect nothing, leading to the conclusion that the Waterwraith's physical form is anchored in another dimension. This is implied further in Pikmin 4, where both Olimar and Dalmo describe the creature's watery form as "nonexistent".

Locations
As stated before, the Waterwraith appears in all 5 sublevels of the Submerged Castle in Pikmin 2 and the Engulfed Castle in Pikmin 4. In the first 4 sublevels, it will drop from the ceiling after a five minute period. In the 5th and final sublevel, it will only fall when in range of its spawning point, similar to other bosses.

Once defeated in the Engulfed Castle, it will not respawn in any sublevel, and is replaced in the final encounter with a swarm of Mitites.

The Waterwraith only appears a few time outside of its caves. In Pikmin 2 Challenge Mode, two Waterwraiths will spawn in the Bully Den when the seconds counter falls to 270, leaving only 30 seconds for preparation. In Pikmin 4, one can be found in the final story of the Trial of the Sage Leaf, The Purple Key. And, much like Bully Den, two will spawn immediately in sublevel 16 of Cavern for a King. These are, however, intended to be fought with Purple Pikmin.

While wandering
The Waterwraith will come on any sublevel of the Submerged Castle or Engulfed Castle after 5 minutes. When encountered, the beast falls from the sky. Once it lands, it lifts up its front roller and smashes it on the ground, crushing any Pikmin underneath. It then commences moving around on its stone rollers. However, before sublevel 5, there is virtually no way at all to harm it; not even bomb rocks or attacking with Pikmin after using an ultra-bitter spray will have any effect. With that in mind, there are a few things to remember:


 * The Waterwraith can kill other enemies and disable traps. This can be used to your advantage.
 * It follows the active leader. This can be used to your advantage, similar to the fight with the Ranging Bloyster.
 * The Waterwraith does not go into small corners, crevices, and dead-ends, making these places safe to hide in. In Pikmin 4, there are specially marked crevices with grass and metal archways that the Waterwraith will be unable to access.
 * In Pikmin 2, if you're having a difficult time avoiding the Waterwraith, you can always reset in an attempt to get an easier or more exploitable floor layout. Similarly, in Pikmin 4, the rewind mechanic can be essential to making more efficient movements around the sublevels or making up for heavy losses.
 * A cloud of dust is visible behind the Waterwraith, allowing you to keep better track of it.
 * In Pikmin 4, the Waterwraith is slow, so running away is easy unless it pins you.
 * In Pikmin 4, The Waterwraith presents very little issue to Oatchi due to his compactness and precise handling, making him ideal for Pikmin transportation instead of letting the Pikmin squad roam free.

The following tips can also be used for Story Mode:
 * You should collect treasures as quickly as possible and avoid collecting corpses. If you're fast enough, you can avoid facing the Waterwraith entirely. Remember that you can return to the cave and collect anything you missed the first time around.
 * It is advised to at least have the Rush Boots power up, which can allow leaders to quickly escape the Waterwraith. The Stellar Orb also helps to illuminate the area, giving you a good view of where the beast is.

Battle
Since it can only be conventionally damaged by Purple Pikmin, the only way to combat it in the Submerged Castle and Engulfed Castle is to survive until the final sublevel, where you can get Purple Pikmin via Violet Candypop Buds.

When a Purple Pikmin lands on or near the Waterwraith in a fashion that would stun any other beast, it turns a deep shade of purple not too different to that of the Purple Pikmin themselves. In this state, it is vulnerable to all Pikmin attacks. When the Waterwraith's health has been fully depleted, the rollers crumble and the creature starts running aimlessly around the cave, no longer a threat to your Pikmin. Attack with more Purple Pikmin and then you can easily attack it with other Pikmin. When defeated, it will vanish into nothing, and you will be troubled no more. In Pikmin 2, tt drops the Professional Noisemaker, a useful addition to the Exploration Kit, the first time you beat it in the Submerged Castle.

The Waterwraith can be petrified, which is useful to stop it if it is coming towards you, but while in this state, it cannot be damaged with normal attacks – Pikmin that attack will just cause an effect similar to attacking a reinforced wall in other games. Purple Pikmin that land with a thud on the petrified creature have a different behavior, however. When the boss has its rollers, a thud can cause the health wheel to appear, if it hasn't already. In the state without rollers, these thuds will actually cause a small amount of damage, and make it possible to kill the creature when petrified.

In Pikmin 4, you can just keep hurling your Purple Pikmin at it and it will get stuck in a loop, but make sure to call back your Pikmin when they get shaken off.

Collin's dialogs
[He opens "The Nonexistent Entity"'s entry in Olimar's Voyage Log.]

Glitches


The Waterwraith is the cause of a few glitches in Pikmin 2.


 * Struggling Waterwraith: by petrifying the creature on the Piklopedia just as its archive is opened, and then petrifying it again just as the rollers break free will result in only the rollers getting petrified, but not the boss.
 * Sliding Waterwraith: By switching between a leader close to a vulnerable Waterwraith and to a leader far away from it, the creature will be seen stuck in the same pose, but moving around like normal.
 * It is likely that if the Waterwraith's head comes into contact with the Research Pod after having lost its rollers, another glitch will occur. The outcome is a change in the way it moves: instead of walking, the creature glides along; and any Pikmin that touch it are thrown out-of-the-way, though unharmed. The amount of health it had previous to the glitch occurring determines whether or not it can be damaged in this state.
 * Another glitch may occur when the Waterwraith attempts to turn around sharp corners. Instead of successfully completing a 360 degrees turn, it may get wedged in the middle of a tight space. This could either be helpful, allowing the player to avoid the Waterwraith, but this glitch could also block crucial pathways, such as a pathway to the next floor. Unfortunately, the only solution for this is to reset.
 * Yet another glitch happens when the Waterwraith is hit with a Purple Pikmin while running. The Waterwraith may turn clear while in the crouching position, instead of it having a purple hue.
 * In Bully Den, the Waterwraiths will never pay attention to Louie, when playing in 2-player mode. This can result in a rollerless Waterwraith to casually walk or even stand still near Louie, instead of panicking. It can still be attacked by Louie, though.
 * In Pikmin 2 Piklopedia, it is possible for the Waterwraith to roll out-of-bounds.

Trivia

 * The Waterwraith is one of three enemies to not appear in the Wistful Wild or any of its caves, the others being the Giant Breadbug and the Toady Bloyster. All three can be found in the Perplexing Pool.
 * The Waterwraith seems to be related to the Plasm Wraith, in both appearance and name. In addition, a possible translation for the Japanese common name of both is "Candy Priest".
 * The Waterwraith is mentioned in Olimar's Piklopedia entry for the Plasm Wraith in, though it just highlights how they are different.
 * In the Pikmin 2 files, the Waterwraith's model contains a dummy texture that reads "fb dum". This is a dummy texture applied to the model before the framebuffer is used to texture it: [[File:Waterwraith dummy texture.png]]
 * In Pikmin 2, if Purple Pikmin are forced to appear in the cave earlier than sublevel 5 and the monster is defeated then, it will still drop the treasure. Despite this, the monster's treasure will not be detected by the radar until the showdown with the beast in the final floor; this is likely to avoid confusion when all the other treasures are gathered in earlier floors.
 * The helpless phase of the Waterwraith, along with the Giant Breadbug and the Titan Dweevil, are the only bosses in Pikmin 2 that have their own boss theme.
 * If the player reaches the final floor of the Submerged Castle before the Waterwraith makes its first appearance, the boss battle with play out as usual, and the ship will not trigger the cutscene to declare it a danger.
 * This is not true in Engulfed Castle, however; after reading Olimar's voyage log on the creature, Collin will state there must be a way to beat it instead of telling the player to run away.