I was playing more Gates, and I got to a cutscene that presented some interesting ideas.
Apparently, Pokemon can alter reality with their minds--in this game, a large amount of negative emotions caused the destructive Bittercold to spawn as a manifestation of everyone's collective negativity. And the world itself has a similar ability where it can spawn the Voice of Life out of its innate desire to survive when it's in grave danger. The Voice tries to protect the world from whatever threat it's facing, and in Gates, this incarnation of the Voice began summoning humans because it believed they could resist the Bittercold’s power better than native Pokemon.
I thought this loredump was cool for a few reasons. First, the potential for Pokemon's minds and emotions to affect the physical world is intriguing (and kinda reminds me of Warhammer). I wonder what the extent of this ability is. I also appreciated how the protagonist isn't the only human. It stokes curiosity about what the other humans' experiences were like, and it prevents the protagonist from being a generic chosen one. Furthermore, the fact that so many other humans were already defeated by the villains adds to the stakes and makes the conflict feel more serious. Lastly, Bittercold's ability to weaken Pokemon means there's actually a good reason why the Pokemon can't solve their own problems, thus necessitating the hero being a human.
However, I have to question why the Voice didn't appear when the world was threatened in all the other PMD games (unless it did play a role and I just forgot). And if I remember correctly, Super's main villain is very similar to Bittercold, so I may have to dock points from Super for being unoriginal if that's the case.