>>39709499A lot of them don't really deserve it.
Incineroar is a wrestler who fights dirty, but he's not evil. Some dex entries even describe him as honorable and having a soft spot for children.
Alolan Grimer and Muk became all rainbowy and spiky because they help to clean up garbage by eating it, which isn't evil at all.
Umbreon is just a kinda scary predator, but a lot of non-dark Pokemon are predatory.
Absol predicts disasters, which gave it a bad rap and makes it seem evil because it looks like it causes the disasters, but they're not its fault.
Same with Darkrai, who passively gives creatures nightmares, so it lives on an island far away from any civilization or even tall grass.