From the Super Mario Wiki
Retrieved from "http://www.mariowiki.com/index.php?title=Swallow&oldid=2119308"
Swallow is one of Yoshi's most common moves. In Super Mario World 2: Yoshi's Island, after catching an enemy with his tongue and swallowing, Yoshi can turn it into a Yoshi Egg. He can also spit them back out, which will defeat another enemy upon contact. In the Super Smash Bros. series, this move is called Egg Lay.
Swallow is also used to eat fruit in Super Mario Sunshine to refuel Yoshi's stomach. Yoshi also eats fruit in other games, such as: Super Mario World and New Super Mario Bros. Wii. In Super Mario World, when a Baby Yoshi eats five fruits, it becomes a big Yoshi, whereas in New Super Mario Bros. Wii, 5 fruits gives the player a Powerup.
"Swallow" is also an alternate name for Kirby's Inhale special move in Super Smash Bros. and Super Smash Bros. Melee. It is Kirby's most important move. Without it, Kirby would not be able to shoot stars and use special abilities.