Quoted By:
Pokemon are naturally aggresive creatures, even if they can learn how to care and love there's no denying that at their core the mayority of them are of violent nature to some degree. That's why it's the human's job to canalize and focus all that energy into something more productive and safe, and the pokemon themselves know about it, hence why they stay with you
It's not a slave & master relation, but more like a coach & a boxer (but of course with how they're marketed they're also treated like pets but that's a whole 'nother topic)
Pokemon like battling, training and working alongside their human companions, and everyone that pushes the idea that the mere act of having a pokemon is cruel is just pushing their edgy 14 yo headcanon or a PETA ninja and SHOULD be ignored