From the very same episode as Pikachu hitting Rhydon with a thunder bolt to the horn, the volcano they fight in erupts. Blane's Magmar is throwing rocks into the lava stream to stop it. Charizard joins in. Two boulders from each Pokemon are thrown at the same time. Then Brock decides to step in, sends out Geodude, who can also only throw one boulder at a time. And Onix.

Onix.


Onix throws a good twenty boulders into the lava river to stop it. How come Brock didn't step up and use Onix before hand?