Final answer:
The Hot Potato plant appears in the Frostbite Caves level of Plants vs. Zombies 2, where it is used to thaw frozen plants.
Step-by-step explanation:
The Hot Potato plant is featured in the Frostbite Caves level of Plants vs. Zombies 2. The Hot Potato is used to thaw frozen plants, making it essential in levels where the gameplay is affected by ice and cold temperatures. Frostbite Caves is the theme where players are likely to encounter snowy and icy conditions, and therefore, it's the world where the Hot Potato comes into play.