Sidestepper
A Sidestepper (referred to as Crab (another crustacean enemy) in Super Mario Advance, in Japan Kani-San) is a red crustacean that scuttles sideways. They are one of the first enemies the Mario brothers ever encountered. If made angry, a Sidestepper will bare its teeth and begin to move much faster than normal.
Appearances
Mario Bros.
In the Mario Bros. arcade game, the Sidestepper is the second enemy that the Mario encounters (the first being the Shellcreeper). They are first seen on Phase Five. Like other enemies, Sidesteppers emerge from pipes and walk on the stage's platforms. They move at the same speed as normal Shellcreepers. When hit from below, a Sidestepper will become angry and speed up. Hit the Sidestepper again from below to flip the enemy over, then run into the crustacean to defeat it. If Mario or Luigi fails to run into a Sidestepper, it will flip itself back over and move even faster than before. Sidesteppers also appear in all remakes of Mario Bros.
Mario Clash
In this game, Sidesteppers come out of pipes and scuttle sideways (just like before). Hit it in the front or back with a Shell to turn it sideways, then hit it in the side with another Shell to defeat it.
Super Mario Advance
Not only does the game make a repolished new version of Mario Bros., but also uses the new sprite in the game itself. Clawgrip is revealed to have been a Sidestepper turned into a monster by one of Wart's bubbles. This, however, makes Clawgrip a mere roadblock, rather than of one of Wart's generals.
Mario & Luigi: Superstar Saga
Sidesteppers make a cameo appearance in this game. During the battle with Hermie III, Sidesteppers will frequently run past in the background. This is their only appearance in the game, and they were probably added in to distract the player from the battle.
Mario Power Tennis
Sidesteppers return in Mario Power Tennis. On Mario Classic Court, the original enemy sprites are used instead of modern sprites. During a Gimmick game, a Sidestepper might walk across the court and trip a character.
Super Smash Bros. Brawl
In Super Smash Bros. Brawl, Sidesteppers appear on the Mario Bros. stage. As in the original Mario Bros., there are red, blue, and purple. Sidesteppers coming out of the pipes and walking downwards. Players can hit the Sidesteppers from below to turn them over, then pick them up and throw them. When a player is hit by a thrown Sidestepper, they directly fly sideways off the screen.
Mario Kart Series
In the Mario Kart Series, Sidesteppers can be found mostly on beach stages where they walk left and right. Here they're only seen as red and have highlights of yellow on their claws. Driving into one will make the player spin around. If a Sidestepper is hit with a shell, star, or bomb it will flip over and disappear.
Trophy Information from Super Smash Bros. Brawl
Crabby enemies taken on by Mario and Luigi. One bump from below wouldn't flip them over, but rather anger them so they moved faster. These pests had to be bumped twice before they could be upended and kicked off the stage. If left alone after being turned upside down, or if there was one left, their speed would increase. They went by the basic name of "crabs" in Japan.