Chain Chomp (unchained)

Chomps are, essentially, chainless Chain Chomps. They are much bigger than normal Chain Chomps, setting the standard for their huge sizes.

Super Mario World 2: Yoshi's Island
Chomps debut in Super Mario World 2: Yoshi's Island. They jump from the background hills and destroy everything that is below them (strangely, Yoshi doesn't lose Baby Mario when hit by one of these enormous monsters). They seem to be unlimited in number on the background hill or they come back to the same hill after jumping. They only appear in certain levels, when a sign with one of them on it appears. Chomp Rocks, which are stones in the shape of Chomps, also appear. Another type of gigantic Chomps called Chomp Sharks also appear.

Yoshi's Story
Chomps reappear in Yoshi's Story, where they act almost identical as they did in Super Mario World 2: Yoshi's Island. They only appear on Jungle Hut, World 4-1. This is also the first game in which they are explicitly named Chomps.

Yoshi's Island DS
Chomps once again appear in Yoshi's Island DS, where they once again serve the exact same purpose as they did in Super Mario World 2. Chomp Rocks once again appear in this game, and another type of Chomp, known as the Stompin' Chomp, appears. They are smaller Chomps that stomp around a set area. Chomp Rocks also reappear.

Mario & Luigi: Partners in Time
In Mario & Luigi: Partners in Time, just as the four heroes are heading through the Warp Pipe to get to the top of the Princess Shroob statue in Shroob Castle, a Chomp leaps out of the basement's sewer water and bashes the pipe, redirecting it's destination to the basement.

Later, as the brothers are about to hit an Exclamation Mark Block to cross a pit of spikes and leave the basement, the Chomp leaps out of the water, eats the block, and heads into one of the five Warp Pipes visible on the map. The player must use the Star blocks that appear to damage the Chomp four times. However, on the final attempt, Chomps fill up all the pipes. The player can tell the correct Chomp apart from the others by looking at which one is barking the fastest. When it is defeated, the Chomp is destroyed and the block heads back to its original position.

Super Mario Galaxy
Chomps appear in Super Mario Galaxy and roll straight off the planetoid, without trying to hurt Mario or Luigi in a similar way as Piranhabons from Super Mario Sunshine. If Mario or Luigi is to step in front of the Chomp, he will be knocked over and hurt. In the Single Player Mode, Chomps can only be defeated with the use of a Rainbow Star, a Stretch Plant, or a Bob-omb. In the Cooperation mode, one player can hold one Chomp's back still while the other player spins it in the front, or one player makes one Chomp stunned while the other collides with it, which will make them explode into many Star Bits.

A new subspecies of Chomps, known as Chomp Pups come out of dog houses, and are found only in the Dreadnought Galaxy.

A Golden Chomp also appears in the Gusty Garden Galaxy; defeating it gives Mario a Power Star. A Rainbow Star can be found nearby.

Super Mario Galaxy 2
In Super Mario Galaxy 2, Chomps reappear along with a new Incoming Chomp known as the Silver Chomp. Chomps first appear in the Flip-Swap Galaxy as the common obstacle there. They later reappear in the Chompworks Galaxy, where they make their most prominent appearance. Two subspecies from Super Mario Galaxy return : a Golden Chomp, as part of a mission, and Chomp Pups.

Mario Kart Wii
A Chomp also appears as a stage hazard in Chain Chomp Wheel in Mario Kart Wii. It rolls around in the mid section of the roulette wheel, and squishes any racers who it runs into, or vice-versa. It looks exactly the same as the Chomps in Super Mario Galaxy.

Mario Kart 7
Chomps also appear on Mario Kart 7 ' s Rainbow Road. They appear on the moon portion of the track, rolling around the area. Players who run into a Chomp are knocked back and, like with every other hazard in the game, lose three coins.

Trivia

 * Chomps make a cameo appearance in Paper Mario, along with many other Chomp-related things. The outline of a Chomp appears whenever Tutankoopa used his crushing spell; most of the time it falls and crushes Mario and his partner, but it also occasionally crushes Tutankoopa himself, making the pharaoh more vulnerable to attack.
 * On the Chomp Saucer Planet in the Good Egg Galaxy, one of the holes that the Chomps come out of is much smaller than the rest. However, the Chomps coming out of this hole are still too large to be Chomp Pups, and bark the same way that normal Chomps do, as opposed to a Chomp Pup's distinctive bark, despite being smaller than normal Chomps.