Plessie

Plessie is a large, friendly dinosaur that appears in Super Mario 3D World and its Nintendo Switch port Super Mario 3D World + Bowser's Fury. It allows up to four playable characters to ride it through certain levels or sections of levels, similarly to Dorrie in Super Mario 64, its Nintendo DS remake Super Mario 64 DS, and New Super Mario Bros. Its name is a portmanteau of "" and "Nessie"; the former is an extinct group of large marine reptiles that are often confused as dinosaurs, and the latter is the nickname given to the.

Design
The official United Kingdom game page for Super Mario 3D World calls Plessie a dinosaur in its description, despite it being named after a plesiosaur, which is not a dinosaur. It is designed after a bipedal, an organism that is also not a dinosaur, and lived much earlier than the plesiosaur. During gameplay, it is around three to four times as tall as Mario, although the artwork made for the Super Mario 3D World Original Soundtrack shows it being around only twice as tall as Mario. Its large belly allows it to slide across the water quickly. The bottom of each foot, including the toes, is fully covered by a white pad. Its back features four darker stripes with rounded borders that are perpendicular to its tail. Its eyes each have an orange eyelid, a white sclera, and a big oval pupil surrounded by an aqua-green iris. The upper part of its muzzle is elongated like that of a, and near its top, there is a white protruding end with two nostrils. Its tail is long and ends with a three-lobed cyan structure resting on the coronal plane. Knotted on the left side of its neck is a red bandanna.

Plessie's design shares some features with the design of Yoshis, such as a bipedal posture with short legs, white soft tissue that spans the lower part of the body, big oval eyes pointing forward with a white sclera, nostrils that are hosted near the top of a round protruding end of the upper part of the muzzle, and a crest on the back of the head, although Plessie's has a different shape than that of Yoshis. They also share the same suffix, -sshi (「ッシー」), in their Japanese names.

The French translation of the Super Mario Bros. Encyclopedia uses the term il (he) to describe Plessie, which could indicate either a male or undetermined gender, as the masculine gender can also have a neutral meaning in French. However, the German translation uses the terms sie (she) and ihr (her) in the same description, indicating that Plessie is female. The German game page for Super Mario 3D World describes Plessie as a Dinosaurier (dinosaur), a masculine word in German, and thus refers to it as male, as can be seen by the use of den freundlichen Dinosaurier and der. In the English version of the summer 2023 edition of Nintendo Magazine, Plessie is referred to as a "he".

Super Mario 3D World / Super Mario 3D World + Bowser's Fury
In Super Mario 3D World and its campaign in Super Mario 3D World + Bowser's Fury, Plessie first appears in Plessie's Plunging Falls, where the characters must ride it through a river to reach the Goal Pole. It also appears in a section of Sunshine Seaside, Plessie's Dune Downhill (where it slides through sand), a section of Deepwater Dungeon, and a section of Rainbow Run. In all of these areas, Plessie must be mounted by all characters for a gate to open. It will then automatically move forwards towards the end of the level or section. If one or more players do not mount Plessie after at least one player has, the rest will teleport onto Plessie after a brief moment.

In Champion's Road, Plessie appears at the end of the stage alongside other friendly non-playable characters to congratulate the player, and cannot be ridden. It also appears in the Super Mario 3D World title screen, and during its credits. Plessie is also the Stamp for Plessie's Plunging Falls.

To control Plessie, players must tilt the control stick on the controllers they are using. Tilting it left or right moves Plessie in that direction, and tilting it up or down speeds Plessie up or slows it down. If any player presses the jump button, Plessie will jump, which can help it move through coin rings or collect Green Stars. If multiple players press the jump button at the same time, Plessie will jump higher relative to the number of cooperating players. This also applies if multiple players tilt their control sticks, which will move Plessie more in a given direction. If Plessie falls off of a course, the number of lives lost is equal to the number of players riding it.

Before and after riding Plessie, the GamePad player (in the Wii U version) or any player (in the Nintendo Switch version) can use the touch cursor to pet it. Doing so makes it laugh and give the player five coins.

Plessie also appears in the Bowser's Fury campaign of Super Mario 3D World + Bowser's Fury with a more prominent role. After defeating Fury Bowser once as Giga Cat Mario, it appears near the Lakeside Giga Bell, and helps Mario traverse the waters of Lake Lapcat by carrying him on its back.

As in Super Mario 3D World, Plessie can swim and slide on the ground. However, the player now has full control over its movements. Additionally, by pressing (while using Dual Joy-Cons or a Pro Controller) or  (while using a single Joy-Con), Plessie wil dive underwater for a short period, a move exclusive to the Bowser's Fury campaign. While underwater, Mario can dodge enemies and Fury Bowser's attacks. After performing a dive, if the player presses the jump button as soon as Plessie exits the water, it will launch forward with a sparkling effect, enabling for faster travel. This action is also featured in an animated sprite of Plessie used on the loading screen for the campaign.

While on the ground and not being ridden, Plessie will move its tail back and forth; the tail has a hitbox that can defeat enemies. Plessie can also defeat most enemies by contacting them while Mario is riding it, and can damage Fury Shadows by the same method. By coming into contact with objects such as Brick Blocks, ? Blocks, crates, and Arrow Signs, Plessie will destroy them completely, and they will not reappear unless Mario leaves and re-enters the island the objects were on. It can destroy Warp Pipes this way as well, leaving only rubble in its place; if it destroys the green Warp Pipe at the bottom of Crisp Climb Castle, the one at the top of the first tower will also be destroyed. If it comes into contact with a moving Green Shell, it deflects it, even if it is moving across the water's surface. If Invincible Mario contacts or rides Plessie, it will also gain his properties for the same amount of time.

When Mario is not riding Plessie, it will appear in the water, diving and resurfacing to be at a location close to Mario. Some of these locations are at small docks close to the entrances of islands. If Plessie contacts the lava on Mount Magmeow, it will disappear and resurface in the water nearby. If Mario rides Plessie into the black goop covering Lake Lapcat, it will immediately dive under the goop and resurface in an area of water without goop, leaving Mario vulnerable to damage from the goop.

Plessie's likeness also appears on Timer Gates and Plessie Medals. Both objects start timed challenges when Mario comes into contact with them, and both types of challenge require riding Plessie to complete.

Plessie must be used in the final boss battle of the campaign against Giant Bowser, where it must ram into his crystal ball to damage it. At the end of the battle, this crystal ball breaks, and Plessie collects the three Giga Bells simultaneously to become. The sheer size of Giga Cat Plessie sends Giant Bowser flying upon contact, defeating him and turning him back into Bowser. The ending cutscene of the campaign ends with the camera zooming out to reveal that said cutscene took place on Giga Cat Plessie's back.

After viewing the credits and returning to gameplay, Plessie permanently remains as, despite returning to normal size. In this form, it can carry up to three kittens on its back in addition to Mario, allowing the kittens to move to different islands. As Cat Plessie, it gains fur and cat ears, its tail is replaced with a cat tail, and the soles of its back feet are changed to resemble cat paws. Giga Cat Plessie is merely a much larger form of this appearance (larger than both Giga Cat Mario and Fury Bowser).

Super Smash Bros. Ultimate
Plessie appears in Super Smash Bros. Ultimate as a support, Novice-class spirit. When it is equipped, fighters gain the ability to remain in water indefinitely without drowning. The spirit battle takes place on Great Bay, against a Giant yellow Yoshi, and the Slider theme from Super Mario 64 plays during it.

Theme music
In the Super Mario 3D World campaign, an ambient theme called "Plessie" plays before mounting and after unmounting Plessie in levels where it must be ridden for the entire duration of the level.

In both Super Mario 3D World and Bowser's Fury, Plessie is given a unique theme while riding it. The Super Mario 3D World theme is an arrangement of "Slider" from Super Mario 64. The Bowser's Fury theme is an upbeat version of Lake Lapcat's theme featuring additional instruments such as violins. While Plessie is moving, further instruments such as trumpets enter.