So what power do humans have in the pokemon world? other than strategic advantage

We see various references to aura power or something similar in humans in the anime implying that they literally power up pokemon moves. In game they reference the bond between trainers and pokemon and it has become observable in battle pokemon often go beyond their limits to show love to their trainers.

The most interesting one I've seen was in the pokemon mystery dungeon games in pokemon rescue team after you defeat Zapdos they exclaim how odd it is that a normal first stage mon and their 1st team could repel a Zapdos. It's then revealed that you are actually a human and for the pokemon listening that explains everything.

But why? What is so special about humans that even in a pokemons body defeating a legend seems possible? In the series pokemon seem to be just a smart as humans in a lot of cases so it cant be just strats.