Frog

Frogs (Japanese: カエル, Kaeru) are a species of animals that live on both Earth and on Mushroom World. It has been shown that on Mushroom World exists both regular Frogs, much like those on Earth, and anthropomorphic Frogs who are sentient and are capable of speech.

Super Mario Bros. 2
Wart from Super Mario Bros. 2, is a powerful Frog king who attempted to take over the world of dreams, Subcon. He is the first Frog seen in the Mario series.

Donkey Kong (Game Boy)
In Donkey Kong for the Game Boy, Frogs are allies of Mario. When Mario is standing on them, they jump up high in the air, allowing him to reach higher platforms while carrying the key. Frogs first appear in stage 4-10 in the Jungle. Frogs can also be taken out if objects such as the key are thrown at them.

Super Mario RPG: Legend of the Seven Stars
The Tadpole Pond is inhabited by large, anthropomorphic, sapient Frogs in the duration of Super Mario RPG: Legend of the Seven Stars. Mallow was raised by the Frogs (specifically Frogfucius) and believed that he, himself, was a Frog as well. The young tadpoles comprise a greater part of the population than the Frogs, of which there are only two.

Super Mario World 2: Yoshi's Island
Smaller Frogs later appeared in Super Mario World 2: Yoshi's Island where they could be seen jumping around in some World 3 levels, they didn't have any effect on the gameplay and were mostly part of the background, also red and green Frogs could be seen in the foreground of swamp stages (they are also unaffected by gameplay and were simply placed in the game for decoration). The game also features a sub-species of enemy Frogs known as Frog Pirates and there was also a Frog Pirate boss called Prince Froggy.

Yoshi's Story
Frogs also appeared as enemies in Yoshi's Story during Stage 4-4: Neuron Jungle. They swarm any Yoshi crossing the lagoon. Although any Yoshi could eat them, Green Yoshi liked them best.

Donkey Kong Jungle Beat
During Donkey Kong Jungle Beat, Frog enemies known as Puchigaeru appear in Banana Kingdom and other kingdoms as well; Donkey Kong can beat them by using the Sound Wave Attack. Each strike would make a Puchigaeru inflate more, and it would start floating. After Donkey Kong clapped enough or punched through it while inflated, the Frog will explode.

Diddy Kong Racing
In Diddy Kong Racing, Drumstick is turned into a frog. He can be freed if the player runs over him in the main hub.

Mario Party 6
In Mario Party 6, some Frogs can be seen in the background of Towering Treetop.

Other Appearances
In Super Mario Bros. 3, there is a Frog Suit that allows Mario to become Frog Mario and Luigi to become Frog Luigi; other Frog-like enemies also appeared Super Mario Land 2: 6 Golden Coins.

Trivia

 * In an E3 demo of Paper Mario: The Thousand-Year Door, Hooktail had a strong dislike toward Frogs, however this was changed and Hooktail was given the hatred of crickets. She is still afraid of frogs in the translated versions of the game other than English.