[Wow, that was easier than he had expected.]

We're brought here to train Pokémon. Those creatures you see everywhere. Catch them, train them for battle, get them stronger. Then, you can go for the gyms in each city. Beat all eight gym leaders and get their badges, and you can challenge the Pokémon League.

[And really, there's no problem with divulging this information. After all, most of it is in the handbook.]