Logic/realism thought: actual Gyms and other battle facilities would likely have Center-class healing facilities on-site, with attendants running KOd or injured Pokemon to them as soon as they were ruled unable to battle. That way, the Trainer can focus fully on the challenge and push their Pokemon to their limits. Correspondingly, battles fought in the wild would see most Trainers be more cautious and recall Pokemon sooner.
Also, there should probably be a way for Pokemon to be aware of the state of a battle when they’re sent out. Either by observing from their Trainer’s side (though that’s more practical with some species than others) or a device that allows them to observe from within their balls.