The big difference between Nintendo vs Sega and Capcom is Nintendo's sequels don't suck, and often change. >.> Unless you haven't played the sequels, then you might not know that. (Ignoring Animal Crossing and Fire Emblem here -_-)
And come on, Nintendo releases new IPs here and there. Pikmin, ChibiRobo, ExciteTruck, ExiteBots, ArtStyle. etc