The only thing that makes this theory weird is the whole basis around having children being what determines you going past the "10" mark; just seems kind of weird and unnecessary, and doesn't really have much evidential basis from Pokemon lore.
It'd be more believable if they actually more explicitly worked in the Evolution angle of the series; the anime already had multiple episodes that actually mentioned pokemon levels existing in-universe (though the only ones that actually think about those are try-hards), and in-terms of the game it can explain why there are "classes" of trainers that look practically identical (you could even say that the younger, inexperienced classes "evolve" into the more experienced ones over time; like a Picnicker or Youngster eventually evolving into a Ranger or Elite Trainer, and an Elite Trainer eventually evolves into a Veteran)
"Unique" characters like Gym Trainers, Elite Four and the protagonists could be explained in the same way there are Mythical and Legendary Pokemon that can either have variants or evolve under certain criteria, with attaining a title basically "evolving" you to a certain state, with Champion being the most coveted title by the Protagonist and Rival classes. Joys and Jennys are obviously special, single-stage evolutions all existing from the same family, that then vary based on the region they're in.
You could even incorporate Ash metaphorically with his Pikachu; both choose not to "evolve" from their initial state because they want to show the world that they can be strong enough from their own hard-fought experiences, so even though Ash still looks like a basic trainer he's actually a Level.100, just like his Pikachu.
...Of course, going by game mechanics, most evolved pokemon are just statistically stronger than their base form, but you can potentially develop strategies that can lead to an unevolved Pokemon coming out on top.
....But that's just a theory.