Crawl

Crawl (ガードン), also known as Guardon Crab, is a badnik created by Doctor Robotnik, which are first seen in Sonic the Hedgehog 2. Usually found at casino or bonus stages, Crawl is heavily armed with bumper shield and pincers.

Sonic the Hedgehog 2
Crawl made first appearance in Sonic the Hedgehog 2, as being featured at Casino Night Zone and making the only enemies in that particular zone. Crawl are seen crawling slowly (hence the badnik's name) back and forth on routes. If the player tries to defeat the badnik in front or above sides, Crawl hides under the shield which bounces the player to backwards, while making no damage to player or badnik. Crawl can only be destroyed by performing a Spin Attack from behind.

Sonic Spinball
A single Crawl appears in 16-bit version of Sonic the Hedgehog Spinball, as it is seen behind two Cluckers at pinball table of fourth bonus stage "Clucker's Defense". In this bonus stage, the player has to destroy Crawl from table by using three balls at the same time.

It is impossible to hit them in front as the pinball balls can be bounced from badniks, while giving 1,000 points from one hit. The player has to defeat Crawl from lateral sides multiple times until it lost its shield and with the last hit, it gets destroyed. Oddly this Crawl doesn't have animal inside of it.

Sonic Rivals 2
A different looking badnik, that looks like Crawl is seen in Sonic Rivals 2, renamed as Guardon Crab. These badniks are possibly created by Eggman Nega and being featured at Neon Palace. Though this version has same attack pattern like Crawl, it can be destroyed simply by jumping at it, even from the front. The card of Guardon Crab is able to get by completing second act of Mystic Haunt with an S rank.

Sonic the Hedgehog 4
Crawl makes reappearance in Sonic the Hedgehog 4, as these badniks return with slightly different models at Casino Street Zone. Unlike in Casino Night Zone, Crawl is not alone while the zone also has Batbots and Bubbles as well. However the attack pattern of Crawl is almost the same from previous games and having also animal inside of it once again.

Sonic Generations
Crawl make another appearance in Nintendo 3DS version of Sonic Generations, as badniks are seen at Casino Night Zone. Crawl appears to have same attack pattern from previous appearances, but doesn't have animals inside of it at all. Modern act of the zone features Crawl badniks at lines and looking to the other side, as the player can use boost to go through.

Physical Appearance
The origin of Crawl's design is unknown. It has a grey, torso-like body, a red or orange head with mandibles (vaguely resembling the heads of insect-shaped badniks such as Buzz Bomber or Caterkiller), and yellow crab-like pincers. It also carriers a shield in the form of a bumper with red background, blue center and yellow / white star in it, which it can use to protect itself and knock the player away.

There are several alternations and detailed changes on Crawl's model, that are made in Sonic Rivals 2, Sonic the Hedgehog 4 and Sonic Generations.

Abilities
As being mentioned earlier, Crawl badniks can basically defend themselves by using their shields on left hand, while the player gets bounced back like bobbins at pinball sections. However these badniks don't simply attack to its target while moving slowly back and forth (it is still possible to hit them by simply running into it). However Crawl does not have protection at back section and which is fatal flaw of these badniks.

Sonic the Hedgehog Yearbook 1992
A single Crawl appeared briefly at one panel in the beginning of Sonic the Hedgehog Yearbook 1992' story "Sticky Problems", as watching from farther off with Buzz Bomber while Robotnik is boiling the "Special Instant Glue", which he will used against Sonic to trying catch and destroy him at the story.

Sonic the Comic
Crawl has made several small appearances in Fleetway's Sonic the Comic, as being part of Robotnik's badnik army. Crawl was also featured on the cover of issue 11 and a pin-up og issue 94. In the issue 55' story The Great Escape!, Sonic the Hedgehog disguised himself as a Crawl in order to access a Badnik Processing Plant along with the other Freedom Fighters. A single Crawl has seen in action in issue 46' story Enter the Cybernik, who was quickly destroyed by Shortfuse the Cybernik before doing any damage. Destroyed Crawl has also seen by the time it was seen in issue 59' story The Seven Badniks.

Trivia

 * There is alternative in-game sprites in Simon Wai's prototype of Sonic the Hedgehog 2, that exist inside of the game's coding. Crawl has different position and holds the shield to the lateral direction, while it doesn't do this in final version. It is also noticed that its pincer is miscolored grey.
 * Crawl's pincers are also seen miscolored grey in mini-game of Sonic Spinball.
 * While Cosmic Casino in Sonic the Hedgehog Pocket Adventure is similar to Casino Night Zone, it doesn't have Crawl badniks in it, which makes spikes and crushing blocks only threat at the zone.
 * Crawl and Asteron are the only Badniks in Sonic the Hedgehog 4, that are not featured in the game's website.