Characters on Mega Man's side
Nick Fury, Mega Man, Proto Man, Eddie, Rush, Darci Roll, Supergirl, Black Panther, Wolverine, Storm, Shadowcat, Rogue, Professor X, Ice Guy, Phoenix/Jean Grey, Beast, Cyclops, Angel, Nightcrawler, Mr. Fantastic, Invisible Woman, Harley Quinn, Deadpool, Cat Woman, The Thing, Human Torch, Spider-Man, Iron Man, War Machine, The Penguin, Cyborg, Captain America, Batman, Black Canary, Robin, Black Widow, Hawkeye, Optimus Prime, Ironhide, Brawn, Arcee, Ratchet and Bumblebee
Neutral
Callisto, Pyro, Magneto, Lady Deathstrike, Dr. Doom, Electro, Green Goblin, Dr. Octopus, Bane, Lex Luthor and Mercy Graves
Characters on Wily's side
Dr Wily, Bass, Treble, Megatronus, Barricade, Shatter, Dropkick, Blitzwing, Shockwave, Soundwave, Thundercracker, Thrust, Skywarp, Kingbot, Tengu Man, Astro Man, Dynamo Man, Cold Man, Ground Man, Pirate Man, Burner Man, Magic Man, Move Cannons, Snowmanbot ("Snoler" in SNES-version), King Tank, King Plane and Jet King Robot
Mega Man 8: Rise and Fall of Kingbot (1st July 2072) (Over a year after Wily's last defeat)
Over a year after Wily's defeat, Decepticons returns again and along with Wily already created Kingbot, new robot masters and mini-bosses. Those other robots are Dynamo Man, Cold Man, Ground Man, Pirate Man, Burner Man, Magic Man, Move Cannons, Snowmanbot, King Tank, King Plane and Jet King Robot. Few of those robot masters also appeared since over a year ago, Tengu Man and Astro Man, comes back. When Metropolis is attacked by Wily's robots, the heroes and Autobots comes back. First of all, Human Torch and Invisible Woman defeats Snowman-bot.
After defeating Snowman-bot, Human Torch and Cyclops defeats Cold Man. Then Iron Man and War Machine defeats Astro Man, while Arcee defeats Ground Man. Later, Pirate Man leads an army of swimming robots, which forces military ships to give up. However, Iron Man and War Machine forces those swimming robots to surrender, then leading Iron Man and War Machine to confront and defeat Pirate Man.
After defeating Pirate Man, Burner Man appears. Ice Guy and Invisible Woman defeats Burner Man.
Later, Iron Man and War Machine defeats Move Cannons, while Invisible Woman and Phoenix defeats Dynamo Man. Then Iron Man and War Machine defeats Tengu Man.
After defeating Tengu Man, while Mega Man defeats Magic Man. Later, Proto Man confronts and defeats Bass again.
After defeating Bass, Kingbot and his giant robots (King Tank, King Plane and Jet King Robot) appears. The Autobots confronts and defeats those robots. Then Decepticons appears again like Megatronus, Barricade, Shatter, Dropkick, Blitzwing, Shockwave, Soundwave, Thundercracker, Thrust and Skywarp. However, Autobots including Optimus Prime and Bumblebee defeats all of those Decepticons, then deactivating them again. When the conflict is over, Dr Wily, Bass and Treble flees, suddenly giving up, while the heroes goes back to their league's home. But the Autobots leaves this city, for now...
Mega Man 8: Rise and Fall of Kingbot; THE END