People are like that with everything. They use strong words as hate because they really don't know what it is.
People may hate things for these reasons:
1) They don't know what it is
2) They're miserable
People complain too much. I can't stand rap music, but I don't complain because fo that. I don't hate rap either. There's no use to hate such things.
I don't hate anyone or anything concrete, but I may feel offended by actions that I consider stupid, like playing online games all day long, but I don't walk around hating it or tell people whatever comes into my mind. I let them do whatever they do, and I don't tell them that I play Pokémon.
There are a lot of things like this you discover are in the same way when you grow older. Some people that are against religion just have to burst out that they don't believe in God and that they believe in Big Bang and that the religious people are dumb everytime religion or atheism are mentioned, as well as some religious people just have to pint out the opposite or something similar. Myself, I believe in God, but I've learned to never tell anyone that I do so, and I never discuss anything with them since they never change. This is the same case with politics and with Pokémon.
The only advantage with Pokémon haters is that they can start to like the game or the show if they watch it, especially if they're younger. As one grows up, the tolerance against new things reduces, and eventually one sit there with one's prejudices and think one has the power to judge everything.
Just let them do as they want to do. Hatred gives one a bad feeling, so the only one they're really hurting are themselves. By hating, you hurt noone but yourself in the long run.
And don't tell anyone you play the game. As mentioned before, that's the best way to protect yourself from any harm.