In Super Mario Odyssey
Poison Piranha Plants can be found in the Steam Gardens. To defeat the Poison Piranha Plants, Mario must throw Cappy at them. The Poison Piranha Plant will swallow Cappy, stopping him from spitting poison. Mario can then jump onto them to deafeat them.
If Mario launches a rock at a Poison Piranha Plant, it will swallow the rock, allowing Mario to capture it. After you capture it, you can spit the rock and poison balls to attack other enemies.