Pokemon: Remnants of a Forgotten past

Break through Rock-Hard Defense

Ash P.O.V.
"We're here!" I said, looking at the tall shining buildings ahead of us. The three had arrived in Pewter City, a city famous for it's archeology and was the place where the first fossil was revived, creating a breakthrough for science all around the world. The city was also home to a rock type gym, famous for its unbreakable defence for years. 

"Let's heal our pokemon and we'll be ready!" said Ash.
"Don't you think you need too wait and train a bit," said Serena. "After all, all the native rock types in Kanto are also partially ground type which is a big disadvantage for you."
"I'll know if I will be able to do it once I do it." said Ash. "Now, no more hesitating."
"Sorry for interrupting, but you know, your friend is correct," a voice came.

We turned and saw someone who must have come from the Stone Ages or something. his eyes were closed and his hair was so shaggy and rough, almost as if they have been kept unkempt for years. Serena shivered a bit upon seeing him, but fortunately for her, the man was focusing entirely on Ash and was thus left unnoticed.

"Who are you?" asked Ash.
"I am Flint," said the man. "I am a jogger."
"Since when is jogging a profession," said Misty, suspicious of this man.
"Never mind that," said Flint. "Now, boy, how many pokemon do you have?"
"Pikachu, Beedrill and Pidgeotto," said Ash.
"You won't be beating the gym leader, Brock is his name, with those pokemon," said Flint. "Trust me."

"It doesn't matter what you think, I am challenging him, and what's more, I will be emerge as the winner." After that statement, Ash went on his way, with Serena and Misty following him. Flint looked on at them.

"You know," said Serena. "He's right. You should probably delay the battle."
"Too late because we're here," said Ash, standing in front of a building which had the iconic pokemon logo. It was grand in size, Ash found.

"More or less amazed you managed to find your way here by yourself," said Serena.
"Me too honestly," said Ash. "Now, Pikachu you ready buddy?"
"(Yes...)" said Pikachu, not very confidently. 

Ash opened the door and went in. He found himself standing in front of a battlefield, huge in size. A few ways ahead, he saw a young teen, about 15 in age, sitting on top of a rock. He was scrutinizing Ash who was coming ahead. When Serena and Misty came ahead , they noticed the gym leader too. However, it was clear to them that Brock did not think much of this new challenger.

"My name is Ash Kechum from Pallet Town, and I challenge this gym!" Ash announced. 
"I accept," he said. "My name is Brock from Pewter City. I specialise in rock type pokemon. Now, challenger, say how many gym badges you possess."
"I don't have any," said Ash, rather sheepishly.
"In that case, according to official pokemon league rules of Kanto, the challenger is allowed the usage of as many pokemon as he wishes if he does not possess a gym badge. Now, let us proceed to the battlefield.

"You think Ash will be alright?" asked Misty. "His team does not match up at all well against rock types."
"I doubt it Misty," said Serena, tremendously worried. "At the moment, there is little more I can expect than the worst."

"The battle will be between Brock the gym leader and Ash Kechum the Challenger. The battle will end when all participating pokemon on either side are unable to battle. Furthermore, substitutions are prohibited on both sides. Challenger, send out your pokemon," said Brock, taking out a pokemon. "Onix I choose you!"

A huge serpentine pokemon built of tens of boulders emerged from the pokeball. It was the biggest pokemon Ash had ever seen, even bigger than the mysterious pokemon he saw the other day. 

"Pidgeotto, I choose you!" said Ash.
Ash sent out the flying type against the Onix. 
"You don't know about type advantages do you?" said Brock.
"Pidgeotto use Gust!" Ash said, ignoring Brock's words