Flying Eggman

Flying Eggman (フライングエッグマン) is the name of the boss fought at Metropolis Zone Act 3 in Sonic 2, where it is piloted by Dr. Robotnik. Flying Eggman has later reappeared as sub-boss of Sky Sanctuary Zone in Sonic & Knuckles and it is the fourth boss at Mad Gear Zone in Sonic the Hedgehog 4: Episode I.

Although it is just Dr. Robotnik in his mobile, Robotnik has seven fake forms of him, that he releases from ball pods (in Sonic the Hedgehog 2 and Sonic the Hedgehog 4). Each time the player hits Eggman's Mobile, one of ball pods transforms to fake one, which can be defeated easily by a Spin Jump. Robotnik also uses a different plan or technique to get rid of the player after removing all ball pods and their fake clones away.

Sonic the Hedgehog 2
Unlike in previous zones, the player will face Flying Eggman in Metropolis Zone Act 3 in Sonic the Hedgehog 2. After crossing huge bottomless pit with forward moving platform and gaining enough of rings, the player is ready to face Doctor Robotnik, who arrives to the arena with seven small spheres orbiting his Egg Mobile. These ball pods protect the Egg Mobile, causing damage to the player if struck, and move in complicated patterns. To begin with, the Egg Mobile descends and moves from left to right along the floor, forcing the player to make difficult jumps over it. After this, it will hover in the center and cause its pods to whirl around in very large circles, which the player can avoid if standing to the very side. Immediately after this is the best time to attack as the pods briefly orbit the Egg Mobile just around the middle rather than whirling all around it.

If the player hits the main body of the Egg Mobile, one of the ball pods will detach and expand into an inflatable copy of the Egg Mobile, while Robotnik himself flies to the top of the screen, out of reach. The clone will float towards the player, and can be easily destroyed with a Spin Jump. Once the clone is destroyed, Robotnik drops down again and resumes its pattern. Once all of the ball pods/clones have been removed and destroyed, Robotnik will fly to one side of the screen and fire yellow laser blasts. Robotnik will keep doing this until the Egg Mobile is hit for the eighth and final time (seven hits are required to destroy the ball pods), which defeats Robotnik once again, who escapes and the player can press the switch on the capsule to complete the zone.

When Knuckles faces Flying Eggman in the locked-on version of Sonic the Hedgehog 2, the battle is notoriously difficult due to Knuckles' poor jumping skills. Unless the player uses Super Knuckles, it is almost impossible to defeat the boss without getting hit.

Sonic & Knuckles
Flying Eggman makes another appearance as the second, recycled sub-boss at Sonic's story of Sky Sanctuary Zone in Sonic & Knuckles. Instead of Dr. Robotnik, Mecha Sonic pilots his mobile this time with seven ball pods orbiting and protecting him.

The reappearance of this boss in Sky Sanctuary Zone used exactly the same attack pattern, as the player has to deal with all seven ball pods and their fake clones, which this time resemble Mecha Sonic on Eggman's Mobile. Similarly after this, Mecha Sonic moves to the corner as trying to shoot lasers from the machine. Like in Sonic the Hedgehog 2, the first seven hits come from hitting him and dealing with the clones and the last one finishes Mecha Sonic. The battle is much easier, as the player now is able to reach and hit Mecha Sonic, who floats on the top and fake one floats around, that the player doesn't need to blow out as he/she can hit all eight times below the Egg Mobile and skip the laser shooting pattern that the Mecha Sonic doesn't get chance to do. After defeating Mecha Sonic who escapes again, a Warp Point appears in the arena's center, that transports the player to the higher levels of Sky Sanctuary Zone.

Sonic the Hedgehog 4
Flying Eggman has made a reappearance in Sonic the Hedgehog 4: Episode I, where it is the fourth boss of the game at Mad Gear Zone but with clear differences. The first part of the fight is just like in the previous games with slight exceptions. The Egg Mobile in the fight is much larger and the ball pods' movement around him is somewhat different. The player is now also able to hit Dr. Eggman directly without releasing off his copies, but the hitbox of the mobile is mostly protected by the ball pods, which the player may hit instead. If the player hits one of the ball pods, they'll come off and try to hit the player, but unlike Sonic the Hedgehog 2 and Sonic & Knuckles, the player will sustain damage if they try to destroy the copies.

If the player manages to hit Egg Mobile four times or destroys all of the ball pods, Eggman will run away by using large rockets below the mobile, while the player has to chase him, similar to the boss fight of Mushroom Hill Zone. During the chase, Eggman himself will throw copies with different attributes. He will throw either normal ones, blue ones (that bounces much faster than normal) or a white-yellow one, that starts off small but expands in varying sizes twice as big as the Egg Mobile itself. Eggman will also throw spiked balls to the route as well. After four hits by using Homing Attack on him, the battle ends, as Eggman escapes and the player heads to the capsule.

The boss battle reappears later in E.G.G. Station Zone, as part of the boss rush before facing the final boss. It is mostly the same chase sequence with identical patterns, while the Egg Mobile can be taken down by doing four hits to him. During the last hit, large hatches on the spaceship starts to open up. After the defeating boss again, the player heads to the last Star Post and the final boss of the game.

Archie Comics
Flying Eggman is featured in Archie's Sonic the Hedgehog comic issue 229, that is part of the Genesis arc., where Doctor Eggman use it to battle against Sonic the Hedgehog, who journeys through the Metropolis Zone to take him down. Before the fight, Sonic starts to remember the world and events before Genesis Wave due Eggman insulting him as "rodent". After this, Eggman releases all small clone duplicates from ball pods to chase Sonic.

Soon after this, other Freedom Fighters manages to shut down the power sources and shutting down all operations on Eggman's base. After noticing this by blackout of the room, Eggman decided to escape Wing Fortress Zone with his Eggmobile while leaving clones still chase Sonic, who will also break out the Metropolis Zone by jumping to the window and landing to the Tornado in time, that is piloted by Tails. They then start chase Eggman to the Wing Fortress Zone, where Sonic catches and hangs on the rocket ship, that Eggman uses it travel to the Death Egg Mark 2.

Trivia

 * The clones do not appear exactly like the original Robotnik, as their mustaches droop a little further down.
 * Same with the Mecha Sonic clones, as they have spines that curve rather than point.