I think some people here are forgetting a few crucial facts about this poll:
Firstly, this was a poll asking fans which companions they wanted Ash to travel with again. While it's true most people will vote for their favorite characters, it's also true that some people may not vote for characters they really like
if they don't want to see those characters travel with Ash again, and that could be for a variety of reasons.
Secondly, this was a poll of
Japanese fans, who are not going to have the exact same opinions of the characters as Western fans do. I've seen a few people attribute Iris's unpopularity to her being a person of color, but that is assuming Japanese fans perceive her that way. Yes, she has a Western name, and yes, she is from a region based off the United States, but this is
anime, people. Look at characters who
are from regions based off Japan. Does Misty, with her orange hair, look Japanese? Does May, with her medium brown hair and blue eyes, look Japanese? Brock has darker skin, and that didn't affect his popularity.
Thirdly, look at the gender ratio of respondents--60% male and 40% female. Males and females are going to have different views on the characters, which is probably reflected in the poll results. Is it a coincidence that the female character with the most votes is the one who is arguably the most feminine?
There is a thing called majority and minority y'know. There's a reason that Iris is ranked last in this this poll. It's a majority opinion that Iris is Ash's worst companion.
No, this just means that the majority of poll respondents don't want to see Iris travel with Ash again. That is not necessarily the same thing, as I explained above.
I will say since it is a website, there may be slight bias there. Maybe only certain people visit that site, like shippers or nostalgics? That's why I'd take the results with a grain of salt, because the people that voted may not be the best representation. Then again, I could be wrong.
The fact that his poll was run by a website may explain the disproportionate number of older fans compared to younger fans. However, that does not necessarily mean these poll results should be discredited. It depends entirely on the polling methods and how the poll designers recruited respondents.