Shellcreepers are enemies and stage hazards in Super Smash Bros. Brawl. They are the ancestors of Koopa Troopas, thus behing a turtle that walks on all fours (Koopas appeared two years after Shellcreepers). It has a green shell protecting it. They originated from the real Mario Bros. game. Shellcreepers only appear in the Mario Bros. stage. in Super Smash Bros. Brawl. They, along with Sidesteppers, will come out of Warp Pipes at the top of the stage and slowly move to outside limits at the bottom of the stage. They will damage and players who physically come in contact with them (excluding attacking them). If Shellcreepers are bumped underneath, they will flip over and try to pick themselves back up onto all fours. Using this time, players can pick up the flipped over Shellcreeper and toss it at opponents to inflict great Damage and Knockback, usually resulting in a KO (especially with high Handicap or Damage Ratio on). However, if a Shellcreeper is not picked up, it will flip itself over and its shell will turn purple. The Shellcreeper will now move a bit faster than before, increasing the risks of coming in contact with them. If a Shellcreeper is bumped again and not picked up, the Shellcreeper will pick itself back up and its shell will turn red. At this time, Shellcreepers move the fastest they can move, and we're talking FAST!! Shellcreepers with red shells will race across the stage at EXTREME SPEED, greatly increasing the risk of being involved in a hit-and-run (being hit by the enemy obviously). Shellcreepers, along with Sidesteppers, have their own trophy showing them in their three colors.
Shellcreeper's Trophy in SSBB
Shelled enemies Mario and Luigi faced back when they were plumbers. They had to be bumped from below to flip them over and then kicked off the stage. The last one on a stage turned from green to red and raced really fast. If one got flipped but not sent off, it would eventually right itself and move at high speeds. They were simply called "turtles" in Japan.
Luigi's clothing color originated (was based on) from Shellcreepers' color scheme.