Then what would an example of a "B" grade title be?
More successful titles (but not mega-hits), such as F-Zero; Kirby; Star Fox (in better days before that franchise got run into the ground); and Pikmin.
In general you can probably break the 3 categories down like this:
"C" Grade - Niche titles that sell to specific audiences, but aren't big money-makers.
"B" Grade - Very successful titles with good production values that sell to a wider audience, but don't have the sales to get the best production values and marketing attention.
"AAA" Grade - (for the platform) ultra-high production values, big marketing attention, very wide appeal, and extremely good sales. System sellers.