Mega Man & Bass feels like an intermediary between Mega Man 7 and Mega Man 8. The irony, of course, being that this game came out after Mega Man 8 did, and the series went back to the Super Famicom after two outings on the Saturn and Playstation.
The main draw to this game is the ability to play through as Bass, who has significantly different gameplay mechanics and boss strategies. In general, Bass has an easier time with the stages thanks to his double jump and multi-directional Bass Buster, while Mega Man has an easier time with the bosses thanks to his lower slide, charge shots, and more useful items.
The game went unreleased outside of Japan for several years before finally getting an internationally-released port to the Game Boy Advance in 2003. For the purposes of this video, I'll be playing a translated ROM of the SFC version (mainly for the larger screen resolution).