All right. This is the common argument that I see when regarding Pikachu.
Pikachu suffers from something that any Pokemon would suffer from if it was listed as the -mascot-
That's right, Pikachu is the mascot. That being said, it's only normal for a company to cater more to the image of their entire franchise.
If Clefairy was settled as the mascot as it was originally planned, people would hate Clefairy just the same.
It's just baseless hate that just bores me at this point.
Secondly, in regards to the light ball. This goes back to Pikachu being their mascot. They wanted Pikachu to be at least somewhat viable without boosting its base stats a ton. Fine, whatever. I don't even think it accomplished that anyway. That's not what bothers me though. If you're going to complain about the light ball then you might as well bring every other Pokemon exclusive stat enhancing item out there. (Thick Club, Lucky Punch etc...) Pikachu isn't the only one with an item like this. You also fail to mention the existence of the eviolite. You know, that item that makes some previous evolutions more viable than their final stage?
tl:dr Pikachu is the mascot, deal with it. That's literally the only reason why it gets special treatment. If it were any other Pokemon, it'd be the same. Most of it is just biased hate.
It's fine to dislike a Pokemon, but to dislike a Pokemon for something like this is petty.
God forbid there's one creature out of the 720+ that you don't like.
You can't be expected to like every Pokemon design, though, putting down a game that you spent 30$ on for one Pokemon is a bit extreme.