From the Super Mario Wiki
“Oracle of the Stars...Mario comes to this island.”
Ravens are black, flightless birds that seem to be both allies and enemies of Mario. Although they are called Ravens, they have almost nothing in common with the aforementioned birds, similar to how Buzzy Beetles are nothing like real beetles. The Ravens of the Mario series are slow-moving, wingless, with elliptical beaks which resemble more a nose than a beak. The only similarities are the coloring of the birds, the sound they make and, only in Paper Mario, their ability to fly.
Super Mario World 2: Yoshi's Island / Yoshi's Island: Super Mario Advance 3
Ravens first appeared in Super Mario World 2: Yoshi's Island, where they could be found walking around large, floating rocks. If they ran into Yoshi, they would send Baby Mario flying off his back. Yoshi can defeat them by stomping on their heads or by throwing eggs to them, but could not eat them. A large Raven named Raphael the Raven seems to be the leader of all the birds.
Ravens make a return appearance in Yoshi's Story. In the game, they acted the same way as they did in their past appearance, but were immune to all of Yoshi's attacks. They appeared in the Tall Tower stage, alongside ComBats. They commonly had Melons on the rocks they walked on, and made a squeaking noise as they did so.
Ravens appear as enemies in Yoshi Topsy-Turvy within the Forbidden Pop-Up Book, which is where the game takes place. They stand about as half as tall as Yoshi, and are always continuously walking. They are not affected by gravity, which is a primary focus of the game. Likewise, they are able to walk along walls and across the ceiling. Yoshi can jump on their head to defeat them. If Yoshi is to come into contact with the side of a Raven, he will lose three points from his Health Meter. Ravens are most commonly seen during the Tale of the Spirit of Power and the Tale of the Spirit of Kindness missions.
Up until Paper Mario, all Ravens seemed to be minions of Baby Bowser and Kamek (influenced by Raphael the Raven's appearance in Tetris Attack), but in Paper Mario, a friendly group of Ravens can be encountered on Lavalava Island. These Ravens (including, oddly, Raphael the Raven himself) help Mario and his party reach Mt. Lavalava. This games also proves that Ravens have their own language (which mostly consists of the word "caw"), although some are bilingual and can speak in human tongues. The Ravens in this game also have the ability to fly by flapping their feet.
Super Princess Peach
Ravens act as enemies serving King Bowser Koopa, who was fighting against Princess Peach this time. Super Princess Peach exclusively gave them Mini-Ravens' qualities and introduced a sub-species known as Sad Ravens.
Names in other languages