How does download work?

Question

The description say "Adjusts power according to the foe's ability." but how does it work?

Answer 1

If this Pokémon is switched into an opponent with higher Defense than Special Defense, it gets a +1 Special Attack boost. If the opponent has more Special Defense, this Pokémon gets a +1 Attack boost. If the opponent has equal defenses, this Pokémon gets a +1 Special Attack boost.