Mega Man 2: The Power Fighters

Mega Man 2: The Power Fighters (ロックマン 2 ザ-パワーファイターズ) is a fighting game released for arcade and PlayStation 2. It's in the continuity of Mega Man: The Power Battle. The player can choose Megaman, Proto Man, Bass or Duo to play with.

Story
Its a disaster: Doctor Light's lab has been attacked by Doctor Wily, and stolen some crucial parts for robots. And, if it weren't bad enough already, he has taken Roll as a hostage! Megaman and Proto Man go to stop Wily, and stumble upon Duo, a big alien robot, who is willing to help. And, Bass is still angry that Wily has revived more Robot Masters, and teams up with the good side to destroy the enemies...

Bosses
and Wily Machine.

Trivia
In Bass' ending, Dr. Wily shows the plans from a new robot he is developing, and it looks very familiar to a certain robot with long hair...