I think you’re definitely on the right track!
Both in the games and in the anime, Protect is depicted as glowing blue energy of some kind that keeps the pokémon safe. The protected pokémon does not feel damage, receive status effects, and so on from being hit. And it is presumably not just a solid wall, so this tells me that the protection, the blue glow, is exceptionally good at absorbing energy.
Capacitors, for example, absorb electric energy. Springs and sponges absorb kinetic (collision) energy, lessening the damage that way. Or perhaps Protect acts more like a Non-Newtonian Fluid (but more like a plasma), which becomes “solid” in the spot that they’re hit, when they’re hit.
So that’s what Protect is. It’s some sort of plasma, which is exceptionally good at absorbing all kinds of energy. The Aura energy, that you mentioned, is described in the pokemon world as “the essence of every living creature”. If Protect is connected to Aura, it would make sense why pokémon have so many diverse types and move. The very living essence of them is able to store all types of energy. It would also make sense why Protect loses its potency after consecutive uses. If the pokémon are using their own life energy to fuel their shield, it’s only natural they get tired.
Thanks!
-Professor Julie
This is super cool!