I really shouldn't tell you this, but the man you know as Hiroshi Yamauchi is secretly a state-of-the-art humanoid robot that was built in Nintendo's secret underground headquarters in the early 50's. He was supposed to be a secret weapon in case Japan went to war with America, but was never used for that purpose. Afterwards, when it became clear there'd be no war, he was made president of Nintendo, to rule like no man could.

Secretly, all of Nintendo's greatest things came from his mind, from the NES to the control stick, and from Mario to Pikmin. He is currently believed to be working on DS2 and Wii 3D.

Yokoi, if only because Tajiri's success wouldn't have been possible without Yokoi's platform.

Gunpei Yokoi all the way. He's largely responsible for Nintendo's transition from cards to toys and eventually to video game consoles. He made lots of great stuff aside from the Game Boy.

But as someone previously said, Yamauchi was also very important to Nintendo.

I'm not saying Miyamoto isn't great. But IMO both Yamauchi and Yokoi are more important than him.

Gameboy was already a multi-millionaire franchise even before pokemon, not to mention that Gunpei Yokoi invented first nintendo console the Game&Watch and inveted the d-pad, only later he created the gameboy. Yokoi was almost as important for nintendo in the past as Miyamoto was. Satoshi Tajiri on the other hand has permitted Gameboy to expand it's life cycle from 1998 to 2001.
I whould choose Gumpei for sure.

Yeah no competition, Gunpei all the way!
He is one of the most important people to the gaming industry as we know it today!

Absolutelty no doubt Tajiri

Yeah the other guy MADE the gameboy

but its Pokemon that sold it, became the most successful anime & IS a phenomenon to this day.

Gunpei Yokoi. No matter how popular Pokemon is, the man invented the damned D-Pad.

BUT PIKACHU!

Gomenasai Satoshi-san. Boku wa Voto Yokoi Gunpei-san!

Faiti Faito!!!

I'm going to have to say Yokoi. His inventions are what helped shape Nintendo to what they are today. (And I do think firing him for the Virtual Boy was a mistake.) Not to downplay Tajiri's acomplishment of Pokemon, but it's been more spun off into its own company, rather than innovating Nintendo itself.