Chopper

Choppers (バタバタ) are piranha-type Badniks created by Dr. Robotnik and make their first appearance in original 16-bit version of Sonic the Hedgehog. This Badnik is not very menacing, but some players can accidentally run into it when they attack from below a bridge and biting Sonic the Hedgehog's feet.

Sonic the Hedgehog (1991)
In their first appearance Sonic the Hedgehog for the Sega Mega Drive, Chopper appears in the Green Hill Zone. It will simply keep jumping from under a bridge trying to hit the player. It is very easy to destroy, and nearly impossible to get hit by one.

In 8-bit version of the game with same name, Chopper has a little different appearance. It will occasionally be under a bridge or by a waterfall with a bottomless pit. In Jungle Zone, there is only one of these that is actually menacing.

Sonic the Hedgehog 2 (8-bit)
Chopper-looking, unnamed Badniks appear at Crystal Egg Zone in the 8-bit version of Sonic the Hedgehog 2. Unlike at their first appearance, their attack pattern is different as they are slowly floating around backwards and forwards and are chomping on empty air.

Being barely threat (or not at all) to the player as they don't come across while player is running. They can be easily defeated with Spin Jump and doesn't have organic battery in it like all Badniks in the 8-bit games.

Sonic Adventure
Although Choppers don't appear in Sonic Adventure, there's upgraded E-series robot named E-28 Mecha Fish, which is one of the fishes that Big can catch. It later appears in one of Sonic's missions.

Sonic Adventure 2
Chopper appears at the unlockable Green Hill Zone stage in Sonic Adventure 2. Instead of jumping up and down like in the original game, he jumps over the bridges in an arching motion. Choppers are more larger in the game.

Sonic & Sega All-Stars Racing
Chopper makes an appearance in Sonic & Sega All-Stars Racing at two of the three Seaside Hill race courses as an obstacle. Like in Sonic Adventure 2 Chopper look more larger than in their first appearance.

Sonic the Hedgehog 4: Episode I
Chopper returned as an enemy at Splash Hill Zone in Sonic the Hedgehog 4: Episode I. Having a slightly different appearance in the game, they normally have the same attack pattern from the first game as jumping at waterfalls.

Sonic 4 Website info

 * First seen jumping out at Sonic from under the bridges of Green Hill Zone, this deadly Piranha robot is back and still hungry!

Sonic Colors
Choppers appear in both Nintendo DS and Wii versions of Sonic Colors, as these badniks can be found at underwater sections of Aquarium Park. Choppers in the game are oddly colored as pink, grey and yellow, though the concept art relates this to Jaws. Throughout the six acts of this zone, schools of Choppers along with very large Choppers infest the many waters that Sonic encounters.

In Wii version, eight Choppers also appear at underwater tunnel section in act 6 of Asteroid Coaster and at several underwater sections in Game Land which are related to Aquarium Park and Asteroid Coaster.

Sonic Generations
Chopper reappears in Sonic Generations as it can be found at Green Hill. The game also features Mega Chopper that destroys the grind rails in a cave in an attempt to catch and destroy Modern Sonic. The Mega Chopper later reappears in Seaside Hill; if the player attempts to abuse the hydroplaning effects of the Sonic Boost and leave the level's boundaries, the Mega Chopper eats Sonic.

Sonic Dash
Choppers make appearance in Sonic Dash, as being featured in Seaside Hill. A single Chopper can be seen jumping on the ocean at same time, as the player has to jump over wide gap between two routes. To proceed with endless running, player has to jump and do the Homing Attack to the Chopper while destroying it for getting to the another side of the gap. If the player couldn't perform Homing Attack in time, the player may fall to the water while losing life or the whole endless running.

Sonic Lost World
Choppers makes another reappearance in Sonic Lost World as regular enemies at Windy Hill. During the game, it turns out that Badniks, Choppers included, got hijacked by the Deadly Six. Choppers, while having more simple design this time, seem to have also similar and simple pattern from previous appearances of the series, as jumping over the bridge from the waterfall. These Badniks can also be found jumping similarly this time on spiral tube sections as well. The player can to destroy these by jumping on them or performing homing attack.

Physical Appearance
Chopper as a Badnik is based on a piranha. They have red mechanical body and does have white dorsal fin, pelvic fins, anal fin and fishtail. Chopper's pelvic fins are set to the body with blue bases. Also Chopper has serrated teeth on its mouth and it likes to wave its mouth all the time. The original design had several bolts in its body while updated designs seems to have added a few holes on its dorsal fin. Also original design used normal white eyes with black pupils, while later designs have black eyes with cyan colored pupils.

In the games, the Chopper's size varies as they can be smaller than Sonic himself, while in later games, they are shown as gigantic and can jump over bridges or small islands.

Abilities
In almost every game that this Badnik has appeared, Choppers reside near a bridge, as it will keep jumping up while trying to hit the player with its chomping, serrated teeth. In Sonic Generations and Sonic Adventure 2, it arches over the bridge. In Sonic Dash, you must attack them with Homing Attacks to cross over large gaps.

Sonic the Comic
Chopper made few appearances in the British publication Sonic the Comic, as a member of Doctor Robotnik's Badnik army but usually getting destroyed by Sonic himself. Chopper has appeared in two covers and two pin-ups during the comic's run.

Adventures of Sonic the Hedgehog
Chopper made a brief appearance in the Adventures of Sonic the Hedgehog animated series. In the episode "The Last Resort", Scratch and Grounder release three Choppers to go after Sonic while he is water skiing. Sonic ends up tying his rope to the Choppers and he water skis behind them.

Merchandise
The toy company TOMY has released Chopper action figurine during the release of Sonic & Knuckles as it also includes a series of 21 Sonic figurines and these figurines came in packs of four under the Sonic & Knuckles label and were also released individually under a Sonic the Hedgehog label.

Trivia

 * Chopper's Japanese name, Bata-Bata, is the Japanese word for a clattering noise, expressing the jaw clutch noises that the Chopper often makes.
 * Chopper appears in Sonic and the Black Knight in winning Fan Art.
 * The Mega Chopper from Sonic Generations resembles a catfish.
 * In Sonic the Hedgehog CD, the Chopper is replaced by the Taga-Taga. Strangely, Taga-Taga only act like Choppers in the Bad Future on Palmtree Panic.
 * Chopper's Sonic the Hedgehog 4: Episode I appearance bears close resemble to Masher as many fans thought to be him when Badnik gets confirmed to the game, because of its look and color scheme.