I don't think importance has to do with it much in smash. First example ice climbers, I didn't know who they were till I saw them in smash. ROB as my second example...a one off console with nothing special about it, sold terribly, and was very forgettable. Duck hunt dog...came out of nowhere, no one was asking for him he just jumped on my screen flipped everyone off and said "surprise b****es!!!" And mr game and watch...I bet most younger people haven't played a single game that he represents through his moveset. And lets not forget the long dead but brought back to life Pit. Only in 2 games, much older than geno, and nowhere near geno level of a fanbase. So in conclusion...what is this importance you speak of? Lol
Ice Climbers is really the only example you have that make sense - and they were chosen because Sakurai wanted to represent an NES launch title.
R.O.B. was crucial in selling the NES in North America. Retailers and consumers alike were deathly afraid of video games because of the great video game crash. But R.O.B. was a trojan horse that sold the NES as a "toy."
Duck Hunt is an extremely well-remembered game across generations, and as Sakurai himself pointed out, is probably the highest selling shooting game of all time. The dog has become a video game icon that almost anybody can recognize, even if they've never played Duck Hunt.
Mr. Game And Watch represents Nintendo's first foray into video games, and even at the time of Melee's release, would be known thanks to the Game And Watch collections on Game Boy. Without this crucial stepping stone, we would not have had the NES.
Pit is the protagonist of a cult classic NES game, which was developed alongside sister series Metroid. Pit was actually a very common request for Smash, which Sakurai noted when he added him to Brawl.
Geno is a supporting character in a single game without much in the way of importance to Nintendo or video games in general. It does have a lot of fans (including myself), but comparing it to those other ones is fairly disingenuous.