But gaming wasnt so centered on consoles then.....I remember the gaming computers were far more popular that Nes in my country(swizterland).I remember the C64,the Schneider(Amstrad CPC),the MSX and the powerful ones the Atari ST and the Amiga.Those were the kings of gaming in Europe in the mid eighties.

Europe worked very differently than the US and Japan for gaming back then because it didn't experience the crash of '83.  This allowed computer/console hybrids to continue to sell unlike in the US and Japan where retailers feared for their lives at the concept of video game consoles.

like its been said, the NES had virtually no competition so they could easily amass huge market share.

 More correctly, they refused to allow competition and therefore they could easily amass huge market share.

Gameboy comes to mind had like zero competition.

 Yeah,but ,whatever the reason ,my points remains valid.The PS2 had a very powerful control over the three markets ....the Nes had a even more powerful control ..but only over two markets as its penetration in Europe was very very small until the very late 80s and even then it was beat by the Master System and the just released Megadrive.

Well there was the Atari Lynx when it came out. Plus the Sega Gamegear later on.

And the closest thing i can think of in terms of monopoly would in terms of electronics would be a Windows or iPod. Nothing came close in console gaming that's for sure. Although idk what the Atari 2600's market share was.

PS2 seems to be close but NES has almost total control over the market.

One of the Ninty portables would have more than 82% - The DS has 63 and is facing the fierciest portable competition Ninty has ever come up against

Well the nes had the biggest dominance but the ps3 has sold 140 mill (vg chartz is off by 20 mil) the nes never reached 70 mil.