Metal Overlord is the fully transformed state of Metal Madness and serves as the final boss of Sonic Heroes. After Team Rose, Team Chaotix, and Team Dark, defeats Metal Madness, the robot completes his transformation to become Metal Overlord and flies off into the skies. Team Super Sonic is used in this final boss battle.
Following the battle with Metal Madness, the creature fully transforms and flies off. Sonic transforms into Super Sonic, using the Chaos Emeralds. He grants Tails and Knuckles super shields, allowing them to fly alongside Sonic.
This battle takes place in the skies. Team Super Sonic begins with 50 rings and they start to drain as time passes. The team must collect balloons while battling Metal Overlord to keep their ring count high, as if the ring count reaches zero, it will cost you a life. Metal Overlord is invincible against all normal attacks from Team Super Sonic, therefore the only solution is to attack Metal Overlord using Team Super Sonic's Team Blast.
Metal Overlord has a variety of attacks, which will require the use of Super Sonic, Tails, or Knuckles to avoid it. He will launch blue crystals, which Super Sonic must destroy using the Homing Attack or the Tornado. The creature will launch missiles from its back, which can only be destroyed by using Tails' Thunder Shoot attack. Also, the creature will launch enormous ships from the Egg Fleet, which must be destroyed by using Knuckles' fireballs. Similarly to Metal Madness, he will launch another type of missile, which forms into crystal cages. If all players are caught in the crystal cages, it will cost a life. Finally, he has an attack called Chaos Control, which will freeze Team Super Sonic for 20 seconds. During this time, Metal Overlord attempts to follow up with another attack to hurt the team.
While destroying the attacks, as mentioned above, it will fill up Team Super Sonic's Team Blast gauge. Use Team Blast 5 times to defeat Metal Overlord and complete the game.