I don't think he's many people's favorite, but even people who never played the games or watched the cartoons are often able to immediately associate Pikachu with Pokemon.
At this point I suspect Pikachu ranks behind perhaps only Mario and Link in recognizability in the mainstream world among Nintendo's characters. Can't say that about any other Pokemon.
*edit* Donkey Kong may actually belong on that list, not sure... Everyone has heard of donkey kong dating back to the golden age of the arcade.
You can't honestly believe that Link is more recognisable than Pikachu? Seriously, you just can't believe that.
I wasn't certain when I wrote it, but I was mostly thinking of the older people who missed the pokemon craze. That window between Link and the pokemon craze may be too small, though.
It'd be an interesting survey to conduct, really... I'd love to know how the characters rank in recognizability among average people. Thinking of all my friends right now, they'd all know both given we were the perfect age for pokemon and smash bros.
Where Pikachu has an undeniable edge is in his name; I'd be willing to wager the majority of those who recognized link would call him zelda lol... Donkey kong's name, meanwhile, is likely more recognizable than his image.
Someone should conduct this survey imo.