Why Pikachu hated Pokèballs.
Pikachu was not your average starter pokèmon. First off, it being an electric type, as well as an evolved pokemon, pikachu was just not a generally common starter. In most regions around the world, there would only be three starters: water, grass and fire, all just barely older than infants.
But this Pikachu, and I'm sure you know the one, was different for several other reasons. It had had a previous owner. This was uncommon, but not altogether unheard of in a starter. Another thing was that this Pikachu had a very interesting personality. One of the things that comes of usually having very young starters is that they usually are very naïve and willing to love any humans as it's mother. Pikachu had once been like that.
Pikachu, then a Pichu, was born to a strong, young pikachu. It was not long after Pichu hatched that he awoke one day without a mother. Pokèmon families are usually very close, and he followed her scent as far as rout six, off of Vermillion City, before he got exhausted and collapsed under a tree. He woke up the next day to the feeling of suffocation and sudden, piercing pain. A seemingly unexplainable rock slide had crushed him against his sheltering tree, and he couldn't escape. He heard a voice through the rocks and tried desperately to plead for help.
"Pi… chu…chu…" he cried desperately, being crushed slowly by the surrounding stones.
"Alright!" he heard, from the muffled voice of a human, something he had never encountered before. "Now use earthquake, Geodude! Go!"
Suddenly the earth around Pichu became unstable and the rocks shifted dangerously. When one hit him on the head, he felt himself give in to the pain and the world around him rapidly faded to black. He heard the stranger shout something else, which was followed by a faint flash of red, and then blackness. Pichu fainted.
The next time he felt his own consciousness return, Pichu had a feeling of much time having passed. All that surrounded him was darkness, and he found that he couldn't move at all. For a while, Pichu accepted it, dreaming, only partially being aware of his surroundings. He knew that he was alright. He knew that the person who had attacked him hadn't been trying to hurt him, but to keep him safe in this darkness. He felt loved and cared for. But he wasn't. It took a while for the young, naïve pokemon to realize that his precious master was leaving him in there as a collectable, not as a companion. Pichu slowly lost track of time, having no idea how long he had been trapped in the darkness. It was no longer safe and comforting, but claustrophobic, ominous and invasive, paralyzing him and keeping him from the outside world to which he belonged. This, surely, was the fate his mother was facing as well. All Pichu could hope was that his mother's master was the caring person he had hoped for.
Then Pichu started to fight back. He had been somewhat aware of his strength before his capture. Now he used it, which was close to impossible in a form that probably wasn't even corporeal. He used up energy and tried for months to escape the darkness. He felt drained of power, but tried relentlessly to break free.
It could have been weeks or years later, but one day, Pichu saw light. It was the first time in a long time that Pichu had seen anything, and it hurt. And Pichu felt something, and it wasn't good. It was like wherever the light was toughing he was materializing. It hurt. There was red, a color he remembered. It had been the last thing he had seen.
Then he heard voices, and one he remembered was among them.
"The pokeball just cracked! It shocked me!"
"What's in that one?"
"No idea… I caught it months ago. Never used it. Don't even know why I kept it. It's probably useless now. Whatever happened to the Pokeball probably killed it. No use now."
"Are you sure, dude?"
"Yeah, I mean, I can't show off a broken pokeball. I can't even sell it."
"I guess you're right. Here, can I chuck it?"
Then Pichu felt the first thing other than fatigue and pain. It was the sensation of being hurled through the air very fast, and ramming into a tree, which, altogether, led him back to pain, but was still an welcome variation. Now Pichu knew that he was close. He could even make out the shapes of large looming objects in the distance. Probably the tree he had been thrown at. He then mustered all of his remaining strength, and forced his way out. This time, for the first time, it took a real form. Lightning.
There was an explosion, and blinding light, first of the lightning, then a mysterious one that encompassed Pichu completely, and then the safe, comforting light of day.
Pichu felt different than when he stood. He was weakened temporarily, but felt like he had changed, and was stronger some how. Upon inspection of his own body, he found that that had changed too. It was the light. He had evolved. The new Pikachu stood for a moment, testing out it's new height, as well as the feeling of supporting his own weight again, but then collapsed against the side of a tree, wincing in pain. The physical exertion as well as having been thrown against a tree, had badly damaged the pokemon. Pikachu felt himself fainting for a moment, and gave out a weak cry. Then he looked up, bleary-eyed, to see the stranger who's attention he had attracted. Through blurry vision, he made out a man in a white coat with an old, wrinkled face and grey hair bending down over him. The man put a leathery hand to his forehead, feeling the fever he was developing, and received a shock and cry of anger from the mouse pokemon. He was a human. Pikachu knew one thing in life, and it was that humans were bad.
In a moment, the hand returned, and the last sight Pikachu saw as he created a spark of protest, was the man's concerned face, followed by a blinding red light. He fainted, but not before he recognized a familiar darkness, different to that of unconsciousness closing in around him.
His first thought upon being released a few days later by the hand of one Ash Ketchum, was that he was never returning to the captivity of a pokeball.