From the Super Mario Wiki
Poison (also known as poisoned water, Poison Bog, or Poisoned Bog) is a liquid hazard found in several Mario games. It is commonly purple, and in most appearances, coming into contact with it will cause the player to instantly lose a life or inflict damage, similar to lava.
Donkey Kong franchise
Donkey Kong Country
Donkey Kong Country 2: Diddy's Kong Quest
Donkey Kong Country 3: Dixie Kong's Double Trouble!
In Donkey Kong Country 3: Dixie Kong's Double Trouble!, poisonous water appears in Poisonous Pipeline. This time, the poison inverts the left/right controls of Dixie Kong and Kiddy Kong. Upon jumping out of the poison, the apes instantly go back to normal controls.
Super Mario series
Super Mario Sunshine
In Super Mario Sunshine, poison appears in a secret area found within Delfino Plaza. In this area, Mario must ride on a leaf down the poison in order to collect eight Red Coins. In this instance, touching the water is instantly fatal. Additionally, in certain episodes of Bianco Hills, Ricco Harbor, and Noki Bay, the water is polluted and can damage Mario.
New Super Mario Bros.
In New Super Mario Bros., poison can be found throughout several stages, mostly in the forest worlds World 4. In this game, it's purple and behaves the same way as lava. Dorrie and Koopa Troopas appear to be resistant to poison.
Super Mario Galaxy
In Super Mario Galaxy, an enormous planet made of poison that can kill Mario instantly is found in the Bubble Breeze Galaxy. It is also found on the Luigi planet from Toy Time Galaxy. An element similar to poison called dark matter appears in Bowser's Dark Matter Plant.
New Super Mario Bros. Wii
In New Super Mario Bros. Wii, poison can be found throughout several stages, mostly in the forest worlds World 5. It retains its appearance from New Super Mario Bros. Koopa Troopas and Big Wigglers are resistant to poison.
Super Mario Galaxy 2
Super Mario 3D Land
New Super Mario Bros. 2
New Super Mario Bros. U
Poison returns in the game New Super Mario Bros. U, where pools of poison surround Soda Jungle, having the same look. Poison also appears in New Super Luigi U. As in New Super Mario Bros. Wii, Big Wigglers are immune to the poison.
Super Mario 3D World
Super Mario Run
Poison returns once again in Super Mario Run, being introduced in the version 3.0.4 update for the game. It appears in the level Spike Bar Jungle of World Star. A new enemy called Poison Bubbles also appear, where they jump in and out of the poison.
Super Mario Odyssey
Poison appears in Super Mario Odyssey, where it can be found in the Sand Kingdom, the Lost Kingdom, and Bowser's Kingdom; touching it instantly depletes the Health Meter. Mario can safely ride Jaxi over poison. In the Wooded Kingdom, puddles of poison can be found on the ground, and touching one of the puddles causes Mario to lose a section of his Health Meter. Throwing Cappy at a puddle will cause some of it to go away, which can reveal invisible coins. Poison Piranha Plants can spit poison, which will create puddles when it hits the ground.
Super Mario Maker 2
Poison appears as a course element in Super Mario Maker 2. It replaces the water in the forest theme when the course is set to nighttime. In the Super Mario Bros. style, poison is dark green, while it is purple in the other game styles. When Yoshi eats a poisoned Cheep Cheep, he can spit purple poison balls which function the same as fireballs, except that they cannot melt Frozen Coins. They also have a different sound effect when spat out.
In Wario World, poison appears in Unithorn's Lair. In this game, it does not damage Wario, but rather cause him to bounce around the room and lose coins while doing so. The poison appears mostly translucent, but with a shining or bubbling surface.
Paper Mario series
Paper Mario: Sticker Star
Poison appears throughout World 3 in Paper Mario: Sticker Star. It is created by Gooper Blooper, and it will disappear once Gooper Blooper is defeated. Wiggler, Snifits, and Cheep Cheeps can stay in it without taking damage.
Paper Mario: Color Splash
Mario & Luigi: Dream Team
Poison appears in Mario & Luigi: Dream Team in Somnom Woods. Falling into it has the same result as the player falling onto spikes elsewhere in the game. Oddly, in this game it appears to be electrified.
Captain Toad: Treasure Tracker
Poison returns in Captain Toad: Treasure Tracker with the same appearance as Super Mario 3D World.