Oddly enough, the japanese poll section that was part of the bigger polls was actually not a real poll, and it was conducted in a tentative at best way. This was push dustin's (from source gaming) putting polls from all over the internet together, and when he tried to find a Japanese poll he couldn't. What he did instead was go on the japanese ballot announcement on twitter and he gauged the responses to mentioned names with a scale of "favorable to unfavorable" based on what was being said around them with varying degrees of accuracy.
Take that part of the poll out and Shantae is now #3 in USA and EU. I would have included this information but my post was already long enough.
Everyone knows that polls aren't indicative of the larger ballot, however, they do show that Shantae has substantial support within core smash communities. Having core support is what made K Rool, Ridley, and Isaac strong presences on the polls and likely the ballot. Those characters are not extremely well known to the bigger casual audience that you are claiming would dwarf Shantae's chances. (except maybe K Rool).
I've said before that you'd only need roughly 20k votes to make it big on the ballot. And if you use the polls as a 1-1 test, you'll see that 50% of all the votes go to the top 20 characters. and after the top 50, there's around 20% of the remaining votes. Considering that Sakurai stated the ballot to have only 1.8 mil votes, we can kind of gauge what shantae would need to place high.
There's a very likely scenario that she did perfectly well on the ballot because of her focused fan support. People banded together to support Shantae as much as people banded together to support Geno. The larger audience is what I feel is the irrelevant data, because they weren't unified, contributing to the tail end of the ballot.
I can mathematically prove that she at least got top 100 if you consider her kickstarter backers as 1-1 shantae supporters and voters. She got around 18500 backers for HGH.
If she got half of her twitter following as voters she's definitely top 20.
As for foreign influence, Shantae's games have been localized in Japan,
she's got enough fans there to warrant two different companies making statues of her (one is going to go for $400) And she made top ten in a recent German poll. It's tough to see how much support she has elsewhere because USA seems to be far more interested in smash polls than other countries.
All this is on top of the large amount of other evidence, which is what led me to believe that she's in the game at all.
If you want, PM me to continue this before we get removed for being off topic by a mod or something.