Both of Takeshi/Brock's Pokemon are of the Ground and Rock element; using Fire or Electrical attacks is useless against them, so rely on your Water or Plant Pokemon to dish out the punishment. You should have no trouble beating Geodude, but Onix can be a little tricky since his Defense rating is so high; save your hardest hitters for him and make sure their HP is near maximum throughout the battle, especially when Onix's BIDE attack comes into effect.

Suggested Pokemon levels: 10+

Items Received: TM01 (Bide)