Blizzard for example had mild success with Rock n' Roll Racing and Lost Vikings prior to Warcraft 2.
Nintendo made lots of arcade games since 1973, many being blatant clones of successful titles, before striking gold with Donkey Kong in 1981. Some of these may have sold fairly well, but the titles are ignored today so they couldn't have been all that good.
Pokemon developer Game Freak seems to have had it pretty rough prior to hitting the big time with Pokemon. The company has existed since 1989 and they put out a number of relatively unknown games before Pokemon in '96. Pokemon wasn't a strong seller at the beginning either.
According to wikipedia (http://en.wikipedia.org/wiki/Satoshi_Tajiri):
"Pokémon Red and Green took six years to produce, and nearly bankrupted Game Freak in the process; often, there was barely enough money to pay the employees. Five employees quit, and Tajiri did not take a salary, instead living off of his father's income. Investment from Creatures Inc. allowed Game Freak to complete the games, and in return, Creatures received one-third of the franchise rights."
Yamauchi certainly deserves credit for realizing that playing cards was not going to be a growth area in the future and for experimenting in new areas that eventually led to toys and then to arcade games.