@BHR, I would rather just have 1 Smash, 1 Mario Kart, and 1 F-Zero per generation. The games frankly wouldn't be as good if they kept shitting them out 2-3 times each generation. They would be way overused (while people are already saying they overuse their franchises). There are a few series that could that they do and should produce more than 1 game for the franchise each generation like Metroid Prime, Mario, Fire Emblem, and many more.
@Soriku, Animal Crossing only have 1 game per generation unless you want to include the DS/Wii but I don't really count handheld and home consoles as being the same (only 1 game per system generation). It would be pointless to release 2 Animal Crossing on the same system though.