Writing exercise time!
Imagine you (or a character you're writing) don't have a Pokémon yet. Maybe you're just a kid who isn't old enough to be trusted with one, or you're an adult with an actual stable job and never had a use for one, or maybe you just don't think you'd be a great trainer. Still, you've probably imagined in your head what the ideal Pokémon for you would be—the noble Gallade, or maybe the sleek and cool Scizor, or the elegant Milotic...
But you don't get any of those. Instead, one fateful day, through a stroke of (bad? good?) luck, you find yourself burdened with a:
https://randompokemon.com/
Generate 1 Pokémon, Unevolved, No Legendaries.Look at their Bulbapedia page, specifically the Biology section and Pokédex entries. What kind of needs do they have? A voracious and exotic appetite? Constant shedding, or need for trimming/shaving? Do they get restless if they don't get to battle multiple times a day? Maybe they can only thrive with certain environmental conditions you'll have to reproduce at home. Everyone wants to have a puppy that also breathes fire, but what does owning one really *entail*? Think about the work that goes into one instead of just the cool things it can do.
How does it end up going? Do you start resenting it, or would it be the kind of thing that you/r character eventually finds a way to handle, somehow or another? Is there some cool positive trait of the Pokémon that makes you warm up to it or that offsets all of the work involved, or do you feel more like you've become a charity worker working your ass off for this thing with no reward? Does it even have a nice enough temperament to feel grateful?