The tournament in Mega Man Megamix.

The First Annual Robot Tournament, known as the First World Robot Championship (第1回世界ロボット選手権 Dai Ikkai Sekai Robotto Senshuken) in Japan, is a tournament in Mega Man 6 held by the World Robot Alliance and sponsored by Mr. X. Powerful robots from several countries enter the tournament, but when it was about to begin (during its final event in the North American manual), Mr. X reveals his plans to conquer the world with eight of its strongest participants, the Robot Masters Blizzard Man, Centaur Man, Flame Man, Knight Man, Plant Man, Tomahawk Man, Wind Man, and Yamato Man.

Other media

Mega Man (Archie Comics)

When Mega Man travels to the future several times in issue 20, he sees two robots (Knight Man and Yamato Man) fighting in an arena, foreshadowing the tournament. This is also the only instance where Mega Man teleports in without actually taking Mega Man's place, presumably because Mega Man was Rock at the time of the tournament.

Mega Man Megamix

As scientists all over the world developed new robots to preserve world peace in hopes of avoiding future disasters like those brought about by Dr. Wily, the Ultimate Robot Championship (第1回最強ロボット選手権 Dai Ikkai Saikyou Robotto Senshuken, "1st Strongest Robot Championship" in Japan) is held to show how powerful these robots are. However, eight participants (the video game bosses) suddenly attack the other robots present, which include Dust Man, Pharaoh Man (he mentions that Dr. Cossack isn't aware that he went to the tournament), Karate 003, Build Man, and Judge Man. Mr. X than reveals his plans and challenges Mega Man to face him in New Metropolis.

Rockman 6 (manga)

The 1st World Robot Championship Tournament.

The World Robot Alliance and the X Foundation hold the 1st World Robot Championship Tournament (第一回世界ロボット選手権大会出場 Dai Ikkai Sekai Robotto Senshuken Taikai Shutsujou) in the Tokio Dome. When the event is ready to begin, Mr. X appears and gives a speech, revealing that the participants must defeat eight seed players to be admitted in the tournament. The eight robots are very powerful and shortly defeat all participants present in the dome.

Everyone is surprised, and a member from the World Robot Alliance asks Mr. X what he is doing. Mr. X reveals that he was manipulating Dr. Wily from the shadows, and now he is going to conquer the world with eight of the world's most powerful robots. One of the participants, Karate 003, rises and tries to stop Mr. X, but Yamato Man stops his Rocket Chop and he is destroyed by a combined attack of Knight Man, Tomahawk Man and Wind Man. Mr. X than leaves the dome with his eight robots, ending the event.