Ill assume youre talking 3D Mario, as you compared it with Halo. To counter this I throw a Gran Turismo in your direction .
Actually not really. I discovered that "time" is a factor in determining the true relevance of "flagships". It is something I like to call "generation sales". Basically how well a franchise sells over the course of the entire generation.
Wii has Mario Galaxy 1, Mario Galaxy 2, New Super Mario Bros if I am not mistaken. Nevermind the spinoff sales like Mario Party or Mario Kart. Mario sold like what......40+ million dedicated Mario games this gen on Wii.
360 Halo sales (FPS ones) are comprised of Halo 3, Halo 3 ODST, and Halo Reach. Combined total of 26+ million Halo sales this gen.
PS3 flagship GT5 only sold 7 million. If you'd like ill throw in the demo for another 4 million for a combined total of 11+ million.
Being a one hit wonder just doesn't cut it nowadays. True flagships deserve multiple games per gen, and sell amazing each time. That is why in my opinion, Uncharted is the new flagship IP, since it now has higher "generation sales" then GT, which is a combined total of 13 million I believe.
Older and wiser. Still bias and proud though ;)