Poochy

Poochy is a dog that has appeared throughout the Yoshi franchise. He can be found in certain levels and serves as a safe platform. Poochy can walk over dangerous terrain, such as spikes and lava. He has a spotted coat with a long red tongue, lips that look similar to that of a duck, and a red (yellow in his Yoshi's Woolly World artwork) ball at the end of his tail. He barks constantly while he walks.

Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
Poochy debuts in Super Mario World 2: Yoshi's Island and reappears in the remake, Yoshi's Island: Super Mario Advance 3 (receiving no changes besides a graphical update). He can run on hazardous forms of terrain and charge through any enemies in his path. Poochy is ridden by jumping on his head and looking in the intended direction. He attempts to follow his rider after they dismount and waits under them if he cannot jump to their location, though he does not enter Warp Pipes and doors. He can also swim through water while carrying Yoshi. If Poochy reaches a wall, he crosses through a gap if one is present (which usually only fits him and not Yoshi), and otherwise tries to jump over it, even when he cannot make it across. While he is jumping, Yoshi can jump off his head. He can be distracted by throwing an egg at his head, which he plays with and does not pay attention to anything else. Poochy only appears in three levels: 1-Extra, Poochy Ain't Stupid, 2-1, Visit Koopa And Para-Koopa, and 3-2, Jungle Rhythm.

Tetris Attack
Poochy appears in Tetris Attack alongside a Grinder as one of Yoshi's opponents. He was originally Yoshi's friend, but went against him due to a brainwashing spell cast by Bowser and Kamek. Once Yoshi defeats him (which involves playing the game's panel-based puzzles against him), he and Grinder are broken from the spell and joins Yoshi as he fights against Bowser. He is then unlocked as a playable character that can fight against the other brainwashed characters. There is no difference in gameplay, as the only changes are the appearance of the player's side and the sounds that play as panels are matched (cheerful barks as opposed to Yoshi's voice).

Yoshi's Story
Poochy also appears in several levels of Yoshi's Story, helping the Baby Yoshis along the way. Although the Baby Yoshis are not able to ride on top of him, Poochy is able to find hidden fruits and hearts. In the levels in which he appears, Poochy usually starts chained to a post that can only be removed by Ground Pounding on it, which breaks the chain and frees Poochy. After being released, Poochy runs through the level and sniffs out hidden items. When Poochy discovers something, he stands by the spot and barks, and the item can then be revealed by ground pounding. After the item is revealed, Poochy moves on to sniff out other hidden items.

Yoshi's New Island
Poochy returns once again in Yoshi's New Island, regaining his ability to walk on hazardous obstacles from Super Mario World 2: Yoshi's Island. He also behaves and is able to be controlled the same way, though he is now able to smash through certain types of blocks and grab items (such as keys) that the Yoshi can then take. He makes only two appearances in the game: first in 3-5, Don't Fear the Spear, which lets him demonstrate his new abilities, and then in 4-S, See Poochy Run!, where he must be used to clear the stage while avoiding maces and spikes.

Yoshi's Woolly World / Poochy & Yoshi's Woolly World
Poochy returns in Yoshi's Woolly World, appearing in Spiky Stroll and Knot-Wing the Koopa's Aqua Fort, and functioning nearly identical as in previous installments, though two Yoshis are able to ride him now and they sit on his back rather than stand. As part of the game's wool motif, Poochy has a knitted appearance.

A purchasable Power Badge makes Poochy available at any course, but because his usefulness is very situational at most courses, it only costs 500 beads to use the badge, making it the cheapest one in the game. However, even when the badge is equipped, Poochy does not appear during boss battles.

Poochy & Yoshi's Woolly World, a Nintendo 3DS remake of Yoshi's Woolly World is virtually the same, with a few additions, including Poochy-Pups that follow Yarn Yoshi around and assist the player in discovering secrets. A Poochy amiibo was included alongside the game.

Club Nintendo
Poochy makes a cameo in the Club Nintendo comic "Rummelplatzquatsch". He appears on the screen of Mario's Game Boy Camera, which supposedly tells the future. After Poochy shows up on the screen, a pack of dogs comes running towards Luigi and urinates on him.

Mario Kart: Double Dash!!
In Mario Kart: Double Dash!!, Poochy makes a cameo as a background attraction of the Baby Park racetrack but does not make a physical appearance otherwise.

Mario Party Advance
A gaddget named Poochy Pal appears in Mario Party Advance. It involves Poochy walking (and sometimes sleeping) around a backyard and interacting with the various objects in it, such as a Warp Pipe that he can enter. The player has no control over what Poochy does.

Super Mario-Kun
Poochy appears as a supporting character in volumes 19 and 20 of the Coro Coro Comics manga Super Mario-Kun. When he first appears, Red Yoshi mistakes him for an enemy and eats him. Red Yoshi releases him in an egg after Mario reprimands him and Poochy emerges unharmed. He accompanies Mario and the six baby Yoshis on their quest to retrieve the Super Happy Tree, and forms a special friendship with Yellow Yoshi.

Poochy appears in volume 19 chapter 5, 愛犬ポチ！みんあのためにかんばるワン！！ (Beloved Poochy! The dog who does his best for everyone!!), and is the central figure in the events of that chapter.

A different Poochy made his first appearance in the volume 4 of Super Mario-Kun.

Minecraft
In the Super Mario Mash-Up Pack in the Wii U and Nintendo Switch editions of Minecraft, Wolves are replaced by Poochy.

Super Mario Odyssey
Poochy appears in multiple hint photos in Super Mario Odyssey. This officially marks the first time Poochy appears in a Super Mario game. He can also be physically found by fishing in Bowser's Kingdom; when caught, Poochy gives a Power Moon to Mario.

Trivia

 * Poochy would have appeared in Paper Mario, as there is a pre-release screenshot, but he was removed from the final game. It would've marked his first appearance in a Mario game.