Grounder

The Grounder is a Badnik featured as an enemy in a few Sonic the Hedgehog games and publications. While Grounders are one of the lesser recurring Badniks, a specific Grounder acts as one of the major antagonist within the Adventures of Sonic the Hedgehog television series.

Grounders are successors of Burrobots, and are similar in design, but are more bulky. They have red and broad bodies with two continuous tracks for legs. On their head, Grounders have two gray bolts for eyes, a white antenna on the back, and a large drill bit for a nose. They also have a yellow neckline, a blue button on their bellies, round shoulders with the early Robotnik Empire symbol on them, and slightly smaller drill pits for forearms. With their drill, Grounders can burrow through the ground, a skill that they mainly use to drill through walls and hit their target.

Sonic the Hedgehog 2 (16-bit)
In Sonic the Hedgehog 2, Grounders are encountered in the Aquatic Ruin Zone. Here, they usually move back and forth on the ground or underwater while their drills are spinning. Though not dangerous on their own, Grounders are placed in very strategic places, such as at the top of paths above the player to block the way. They can also be hiding inside walls, but suddenly emerge from them when Sonic or Tails passes by. Either character can quickly defeat a Grounder using the Spin Attack or Spin Jump. Like several other Badniks, Grounders release an Animal upon being defeated.

Sonic the Hedgehog Pocket Adventure
In Sonic the Hedgehog Pocket Adventure, the Grounders are featured at Aquatic Relix Zone. In this game, they have the exact same attack pattern as in the 16-bit Sonic the Hedgehog 2, and still release an Animal upon being defeated.

Sonic the Hedgehog Yearbook 1992
Large variations of the Grounders appeared in the Sonic the Hedgehog Yearbook 1992 story "Big Trouble." In it, Sonic and Tails encountered a large Grounder as it broke through a wall. The duo tried to damage it with the Spin Attack, only for it to bounce off of its shell harmlessly. Robotnik then announced to Sonic and Tails in his Eggmobile that this Grounder is the first of a new series of giant Badniks whose size and strength would assure his conquest of Mobius.

Tails wonders if they have to fall back, but Sonic refuses. With a little lateral thinking, Sonic and Tails climb to the top a column high above the Grounder. They then both leap down and hit the Grounder on the head with the Spin Attack, destroying it and releasing the three Animals that served as this Grounder's organic batteries.

Archie Comics
In Archie Comics's Sonic the Hedgehog comic series and its spin-offs, Grounders are Badnik models created by Dr. Eggman. A notable Grounder unit and his associates in particular once served as members of the doctor's Super Special Sonic Search and Smash Squad until they were solid to Breeze Media. The remaining Grounders would serve the villain's army as rank-and-file soldiers.

Sonic the Comic
In Fleetway's Sonic the Comic, the Grounders were a part of Dr. Robotnik's Badnik army. During his initial reign over Mobius, they were only utilized on one occasion: to help the doctor break into Sonic's Secret Underground Base.

IDW Publishing
In the Sonic the Hedgehog comic series and its spin-offs published by IDW Publishing, the Grounder is a mass-produced Badnik model created by Dr. Eggman. Its past is virtually identical to its game counterpart's, up until after the events of Sonic Forces.

Adventures of Sonic the Hedgehog
In the Adventures of Sonic the Hedgehog television series, a green Grounder serves as one of the main antagonists of the show. He was created as the younger "brother" of Scratch and is one of the main subordinates of Dr. Ivo Robotnik, created to be a part of the Super Special Sonic Search and Smash Squad whose purpose is to eliminate Sonic and aid their creator in his various schemes. However, this Grounder is incredibly stupid and gullible, and often ends up causing his allies more trouble for the doctor's plans when trying to stop Sonic. However, he possesses various useful gadgets and an arsenal of weapons.

Trivia

 * In the 2013 remaster of Sonic the Hedgehog 2, a green Grounder appears as a new object in Debug Mode, most likely as a nod to the Grounder from Adventures of Sonic the Hedgehog.
 * Grounder is one of the few Badniks in Sonic the Hedgehog 2 to feature an early version of the Eggman Empire's symbol, which can be seen on its shoulder armor.