Chapter 1

"Oh wow! I got a Pikachu!" She'd exclaim, her face lit up with glee "I always wanted one of these!" She'd say, holding the Pokeball close and begin to head home, as it was the end of the day for her. When she'd get home, she'd let the Pikachu out and giggle, watching it stumble about a bit, and looking up at it's new Trainer. She'd reach down and rub it's head "Pika!" It'd say, looking happy as she did so, and she would then head off to bed, deciding to let the Pikachu stay out of it's ball for the night "Hm... I already have so many strong Pokémon... I know that I have an Electric type better then it, but still... I don't want to just get rid of it." She'd say "...Maybe i'll just let it stay home." She mutters, heading off to sleep, meanwhile the Pikachu was getting used to it's new home, running around and tiring itself out, before it laid on the couch and slept. When it'd wake up, it would see it's Trainer getting ready to go, and the Pikachu would approach her "Good morning lil' guy!" She'd say and pet the Pikachu "Pika-Pi!" It'd say "Would you mind if you stayed home for now?" "Pika?" It looked confused "I still like you, and I still want to keep you. I just don't really want to take you on battles with me." She'd say "Is that ok for now?" "Pika!" It'd agree, believing she'd come back and take them to a fight later, hopefully. She'd nod, smiling "Good! Now, there should be enough food for while i'm gone, so don't worry!" She'd say, smiling as she left and closed the door behind her. The Pikachu looked around and went into the kitchen, seeing all kinds of cooked food and baked goods stored up, and some food even on the table. It assumed this was the food she meant, and hop onto the table and begin eating. It tasted amazing! It continued to eat the wonderful food, wanting to eat all the food that was on the table. It just tasted so good! So it kept eating, stuffing itself with most of the food, becoming greatly full as it's stomach became a large bump on it's frame and the Pikachu would sit down, "Pika..." It'd say, laying down and resting it's paws on it's stuffed belly, before falling asleep to let it all digest. Little did it know, that a strange robot, registered to take care of the Trainer's Pokémon at times, had been watching and absorbing data from the display it had made, that data being stored as how to take care of the Pikachu...

(So... how'd I do with this? First time I've done a Pikachu weight gain, or a Pokémon weight gain in general.)