Clucker, referred to as Kokekko (コケッコー) in the Japanese manual, is a chicken-shaped Badnik from the 16-bit version of Sonic the Hedgehog 2 found in Wing Fortress Zone. They shoot eggs from a turret. Jump on their head to get rid of them; their base remains after being destroyed. "Kokekko" is the Japanese equivalent of "cluck".
Two Cluckers made an appearance in front of a lonely Crawl in the "Clucker's Defense" Bonus Stage in the 16-bit version of Sonic Spinball. The two Cluckers will do whatever they can to defend the Crawl using the small bumpers on their turrets (which replace their cannons) which can bounce back pinballs. While the player can't hit them from the front, they can hit them by their sides to score points.
The enemy reappeared in Sonic Pocket Adventure's Aerobase Zone. They also reappear in Acts 2 and 3 of Sky Fortress Zone in Sonic the Hedgehog 4: Episode II with a modified design, but with the same attack pattern.
They appear again in all versions of Sonic Lost World with a new cartoon-style design, and this time not in aerial areas. In the Wii U/PC version, they appear in Tropical Coast Zone 3 and Lava Mountain Zone 3 in their usual turrets, while also appearing in mine carts in Silent Forest Zone 1. Some Cluckers will even control bulky, spider-based vehicles that will flip when Sonic moves about in the tubular caverns of Silent Forest Zone 2. Just like in all of their previous appearances, they will shoot projectiles at the player.
They appear once again in Sonic Mania, but this time in Flying Battery Zone, specifically in Act 2 which makes callbacks to Wing Fortress Zone in the outdoor areas. Their attack pattern is the same.
||A Chicken type Badnik last seen defending "WING FORTRESS ZONE" in "Sonic 2". They will stand in Sonic and his friends' way, deployed everywhere within the incredibly enormous "Sky Fortress" as fixed batteries.
— Sonic the Hedgehog 4: Episode II website