Oh right. You know, I never really thought about that that way. The TMs and tutor moves. And I guess for smaller, more vulnerable Pokémon like Caterpie, being with a trainer improves their survival rate. They stand a better chance of making it to their Butterfree stage without being eaten by a particularly wily Pidgeotto or something.

Still, though, for as many advantages over us as they have, it really doesn't seem like most of them are particularly inclined to take them.