You keep getting in my way, you pesky little hedgehog! (...) Very well... I'll take you out myself!
— Dr. Eggman, Sonic the Hedgehog (2006)
The Egg-Wyvern is a large robot that is similar to the creature of the same name: a breed of giant dragon native to Africa. It is completely red with spots of silver, white, and black here and there. Its lower jaw is actually the Egg Mobile used throughout Sonic the Hedgehog (2006) that is simply attached to the robot's neck.
After Sonic made it to Dr. Eggman's cockpit on-board the Egg Carrier to rescue Princess Elise knowing that it would crash, the doctor had finally lost his final straw and decided that it was time to settle this dispute with a final showdown against Sonic. In the end though, Sonic was able to defeat the robot and send Eggman spiraling into the sky on his detached seat.
The Egg-Wyvern has a decent assortment of weapons. It uses its whole body as a weapon in the boss battle with him as it is able to charge at Sonic in the hopes of taking him out. The glowing red horn on its head may however have been the real thing that was to serve as a weapon despite the fact that all Sonic had to do was strike at it with a Homing Attack to latch on. It fires a random assortment of lasers down at Sonic from the laser emitters on its wings. It will strike with the wing lasers in hexagonal or rectangular patterns, or attempt to target Sonic directly. At another point it flies around the platform and remotely commands the Egg Carrier to fire large red plasma blasts at Sonic. And throughout the course of the battle it fires electric dart projectiles from its tail that are able to take out the platforms Sonic stands on.
The battle takes place on-board a large aerial platform in the skies that gradually shrinks in size throughout the battle. When the battle begins, run around the platform to pick up Rings while Dr. Eggman gets in position to buzz the player from overhead. When there are a few orange target reticles displayed on the platform, the player should avoid standing on them as they indicate where the Egg-Wyvern will fire its lasers at. When Dr. Eggman strafes the platform, he swoops down low enough to clip the player; they should jump and aim a Homing Attack at the head where Sonic jumps up and grabs the horn at the nose of the Egg-Wyvern. Much like the battle with the Egg-Cerberus, the player is able to temporarily control the Egg-Wyvern's flight. While in control, the player must steer it into the falling fuel canisters to damage it. If the player succeeds or takes too long in their attempt to damage it, they will get thrown back to the platform and the battle resumes as normal.
Sometimes when the Egg-Wyvern flies around the platform, Dr. Eggman remotely commands the receding Egg Carrier to rain down massive blasts down at Sonic. Afterwards, Dr. Eggman ﬁres two electric darts at the platforms. When the player sees the electricity crackling around the platform, back away because that section of the platform is about to fall.
After the player successfully steers the Egg-Wyvern into fuel canisters three times, the canopy (the top of the Egg-Wyvern's head) falls off, leaving Eggman exposed. At this point, the Egg-Wyvern's attacks changes. From here, Eggman will try to attack by detaching the Egg-Wyvern's cockpit laser cannons away from the platform. However, this lets them serve as steps for the Homing Attack and allow the player to attack Eggman's cockpit. As he attacks, Eggman will constantly aim at Sonic before firing all of its lasers. With limited space to run on, the player must get uncomfortably close to the platform’s edge to avoid being shot. After three more hits, Dr. Eggman will sweep in for a ﬁnal attack, during which the player must use another Homing Attack to ﬁnish him.
- It is possible to finish the battle in less than one minute by utilizing the Sky Gem. If the player throws the Gun Drive just a little before grabbing the Egg-Wyvern's antenna, the camera will zoom in at Sonic's direction with no way to change it or to see the robot. After some time, the results screen will appear as if the player defeated the boss.
- The Egg-Wyvern boss battle reminds many fans of the Egg Viper boss battle from Sonic Adventure. The reasons may be due to the color of the robots, the high elevation, the destruction of platforms, certain points where the player is able to hit Eggman directly, and the fact that they are both final bosses.
- At some points during the Egg-Wyvern battle, Eggman will say "Can you make it here?!", similar to a line when fighting the Egg Viper: "Let's see if you can make it through here, Sonic!". Both of these quotes occur when you have to use the Homing Attack to reach Eggman.
- In addition, the Egg-Wyvern may be a throwback to a similar boss concept for Sky Chase. The key difference between these battles is that Sonic is on suspended platforms surrounding the Egg Carrier, whereas the Sonic Adventure version would have likely been a minor boss for the Tornado.
- Before the end of the boss fight Princess Elise says "Sonic! Watch out! He's still trying something!" This is similar to the warning Tikal gives to Sonic in Sonic Adventure, saying "Watch out! He's up to something."
- The Egg-Wyvern is the only final boss of Sonic the Hedgehog (2006) which is not fought multiple times in the story, unless one counts Solaris as a separate entity from Mephiles and Iblis; Iblis is fought at the beginning and end of the Silver Episode, and Mephiles is fought both midway and at the end of the Shadow Episode.
- The Egg-Wyvern is very similar in design to the Egg Hawk, Egg Falcon, Egg Eagle and the Egg Dragoon.