I'm going to give you a stranger challange. You're going to fight Brock with whatever is given to you, and however you're told to do that fight. Depending on how many turns it takes during your sucessful fight against Brock determines your challange.
-2 Turns-MachoMacho the Machop. Can only use a specified type, or types of move(s) determined by an RNG, 1 gets you Normal, 2 gets you Fighting, 3 gets you 4 moves, all different types, none of which can be Normal or Fighting.
-3 Turns-Nohtyp the Ekans- Must have and keep 3 Non-Attacking Moves ASAP. Solo any Rival battle to evolve.
-4 Turns-DontBCruel the Tentacool- Can never evolve. Must solo 5 Trainer Owned Tentacools/Tentacruels to learn/use Water Moves.
-5 Turns-Agony the Grimer- Must solo Koga.
-6-20 Turns-CoolWhip the Tangela- Must solo an Elite 4 Member only using hold items.
-21+ Turns- If you can actually stall out a battle with Brock for 21 Turns, that's crazy. You can use whatever Pokemon you want, named whatever you want, that can't use TMs or HMs. Move Tutors are fine though.