Mega Man returns to Game Boy Advance in a port of 1998's Rockman & Forte on the Super Famicom, a game originally released for the Japanese market. The title chronicles the unlikely alliance between the Blue Bomber and his former nemesis Bass, a character introduced in Mega Man 7, who finds himself cast aside from Dr. Wily's nefarious plans. In his place Wily has assembled a more powerful robot named King, designed from the ground up to conquer the world. As either Mega Man or the spurned Bass, players begin a quest to put an end to Wily's plans once and for all. Yet before the inevitable confrontation with Wily and King, they must first defeat eight robotic creations in classic Mega Man fashion.

As in previous games in the long-running series, Mega Man & Bass involves advancing through eight themed worlds until the eventual showdown with a boss character. Once defeated, the boss will relinquish its special weapon, which can be used on subsequent enemies. Weapons include the Ice Wall, Wave Burner, Remote Mine, Spread Drill, Lightning Bolt, Tengu Blade, Magic Card, and Copy Vision. Mega Man & Bass also features each character's mechanical sidekick, Rush and Gospel, who can help them throughout the game. To further assist players, screws can be collected on each level and used to purchase helpful power-ups from friendly robot Lightott's item shop. Two distinct endings are also available depending on the character selected.