>>54221882Fags argue over two fictional characters will always be above me but I'll bite. Iris' main haters steams from Ashfags and Cynthiafags.
I'll start with Cynthiafags. Essentially it's the same reason they hate Leonfags. While Leon is a threat to Cynthia's title as the "strongest Champion", Iris is the only other prominent female Champion. Nobody gives a shit about Diantha (nor does the anime team just by looking at the PWC) and Getta is the same.
Iris would be in the same position if not being the starring heroine of her own series and her voice actresses raising to mega star fame since Best Wishes. She's not more popular than Cynthia in the fandom in general but more identified when it comes to the anime. There was a reason why they payed her actresses big bucks to pay one of the most hated characters. So in short Cynthiafags can't handle another female Champion that didn't fade into the background.
Ashfags feel robbed. Imagine watching a character take about 7 or so series to become Champion and then anther series to become amongst the strongest in the world and another character pops up and goes "easy peasy" in the next two episodes she appears in? Iris got everything people wanted Ash to have with less than half the struggle or time taken.
Ultimately her rise to Championship didn't much sense but when you take into the narrative reason why it happened (Alder's voice actor not being available) and Iris' voice actor being a big name willing to return, it makes sense. Just like narrative wise Cynthia had to win. Not because she necessarily be stronger than Iris but because she and Leon as the star of generation Eight, had to fight Ash. That's literally the reason but it's better arguing who's strongest I guess when all of this is narrative.