I guarantee them choosing to have Pokemon say their name in the main line anime was a marketing strategy so we’d all know them better, or else it’d be weird that Pikachu was the only one going “pika-pi” while everything else were actual creatures.
In the Generations series on the Pokemon official YouTube, every 'mon has some sort of animalistic cry and it sounds so much more natural than if your Arcanine just repeated “arc-arca” instead of having different growls or sounds to communicate with a trainer.
But here’s a spinoff question, to what degree can Pokemon and humans communicate? We know they understand us, enough to obey commands, but can long term partners have more effective communication? Predicting thoughts or even reading them? Could you use a Psychic type off the field during a battle to relay your thoughts to your battling Pokemon, making it so that your opponent couldn’t tell what you’re planning because you’re not yelling out your next move?
Wasn’t Ash-Greninja proof that humans and Pokemon can indeed have a much deeper connection? Even in some earlier episodes we saw Sabrina and her Kadabra had a really strong bond. There is also a scene in the anime spinoff (maybe it’s called Pokemon Generation) where Lance and his Dragonite are raiding the Team Rocket building and all Lance has to do is nod and Dragonite basically knows what to do next.
I think it depends on the bond and level of trainer but it should be possible.
I vaguely remember an episode where ash threw a pokeball and brock got in the way and it basically zapped him but didnt do anything. I may be wrong. It did capture a “donut” though, weird.
I remember a line in the video games saying people were originally Pokemon years ago. Could you therefore catch a person in a Pokeball and make them do your bidding?