Doctor Robotnik's Whirlpool Machine

Big Shaker (ビッグシェイカー) is a mini-boss from Sonic the Hedgehog 3, as well as its locked-on form, Sonic the Hedgehog 3 & Knuckles. It is encountered in the first act of Hydrocity Zone.

Attack Pattern
Big Shaker is fought in a bowl-shaped arena half-filled with water. Little missiles, which presumably are thrusters for the robot, orbit its central body acting as a shield as it charges down both sides of the arena. After finishing that, Big Shaker settles down on a pole-shaped turbine in the middle of the arena, allowing a few seconds in which to attack but quickly turns the pole which stirs up the water and Sonic and/or Tails (see screenshot), rendering them unable to do anything until the stirring stops.

Hits can be scored until Big Shaker starts up its thruster missiles again, after which the whole process repeats. Sonic can score the six hits needed to defeat this boss before the stirring starts for the first time with the help of a Bubble Shield.

Knuckles' Battle
This mini-boss, like all the ones from Sonic the Hedgehog 3, can be fought with Knuckles in the complete, lock-on game Sonic the Hedgehog 3 & Knuckles. Most mini-bosses and major-bosses are increased in difficulty for Knuckles. In this case, the attack pattern remains the same, but is made more difficult by Knuckles' reduced jump height. He can jump over it, but not by much. Knuckles is unable to jump high enough to get above the surface of the water so must Spin Dash up one of the sides periodically to prevent drowning.

The battle can also be made a lot easier for Knuckles, however. If Knuckles climbs up the right side wall above the water before Big Shaker begins its sweeping attack, and dodges that attack by gliding to the opposite wall twice, Knuckles can jump off the wall and bounce on Big Shaker from above for an easy kill while he is doing his whirlpool attack.

Trivia

 * When the drowning music plays in the standalone Sonic the Hedgehog 3 version, jump back above the water and the Sonic & Knuckles mini-boss music will play.
 * It is possible to drown whilst fighting this boss, as the 30-second limit still applies, although it is not possible to drown whilst the score is being tallied.