Taken from Pokemon Indigo
Cole causally entered the gym, Spirit and Amber trailing behind him. The room was similar to the inside of a cave. Tall pillars of rock stretched up to support the roof, and a path led around large boulders and up a set of stairs to the Gym Leader.
"So, you think you can defeat me?" Brock asked. "Well, I see you're brave, coming in here with Pokemon weak to Rock-Types. What kind of battle would you like, kid?"
"Two-on-two, double battle," Cole replied, and his voice echoed throughout the room.
"Very well, then. Follow me to the arena."
The arena itself was a large, oval-shaped room that vaguely reminded Cole of a basketball court.
"Stand back, now," Brock said, and the arena sunk into the floor. What replaced it was a mountain of rocks and boulders, transforming the arena into a Rock-type's paradise. "Let's get this done, then."
Cole and Brock walked to opposite sides of the court.
"Amber, Spirit, show him who's boss!"
"Geodude, Onix, give him a taste of our hospitality!"
[I]Two Rock-types,[I] Cole thought, racking his brain for ideas. If one of them had been a Sandshrew, a good Ember or Fire Spin might've taken it out. But Brock is probably going to use a primarily offensive strategy, which means it doesn't matter who I target first.
"Amber," Cole said, "Use Confuse Ray on Geodude!! Spirit, Sand Attack on Onix!"
"Amber launched a flashing blue-and-purple at Geodude, who immediately stopped and sat, mesmerized by the lights. Meanwhile, Spirit flapped his wings and sent a great cloud of grit and sand at the Onix's eyes, which were now screwed shut.
"Gah," Brock said as his Pokemon were hit. "You have a good strategy, I'll admit, and those Pokemon look higher leveled than those of most Trainers who come here. Geodude, Tackle! Onix, Bind!"
Geodude proceeded to slam his head into the nearest boulder multiple times, while Onix dove randomly and ended up several meters away from the nearest enemy.
"Switch it up, you two!" Cole commanded; Adrenaline was making him feel almost giddy at his enemy's moves failing. "Amber, Confuse Ray on Onix! Spirit, Sand Attack on Geodude!" Both performed their moves well, leading to two confused and blind Rock-Types.
"I'm not even going to pretend this is going to work," Brock admitted. "Geodude, Tackle! Onix, Rock Tomb!"
Geodude actually managed to charge in Amber's general direction, but a simple sidestep left it running headfirst into a pillar of rock. Onix, on the other hand, attempted to use the Rock Tomb on himself. And missed.
"Amber, use Ember on Onix! Spirit, keep hammering down Sand Attacks!"
And so it went on, miss after miss and Sand Attack after Sand Attack, until Cole walked out of the Gym admiring his new Boulder Badge. He'd only needed to use one Potion, when one of Onix's Rock Tombs had landed successfully and Amber had almost fainted. But now Cole rushed into the Pokemon Center to heal his Pokemon, and then he would be training until evening, when he would go watch Camille at her Contest.