Pokémon mystery dungeon

What lies inside part one

"It's really it! The fabled cave!" Thunder yelled as he ran around.
"Shut up and follow me!" Spark said making Cocoa smile.
"Why should we!" Finch said with a smirk.
"Because I'm the one with lights on my ears, legs , head, and tail." Spark responded.
They followed when faced with reason and soon got to a monster house.
"Don't go in there!" Cocoa yelled and tried to grab the inexperienced spark but it was too late... the wild Pokémon had noticed them.
"Get out of our cave!!!" The Pokémon yelled in a flurry of attacks.
The group fought them off because these Pokémon were weak from never having anyone to battle.
Soon the group got to a hallway and decided it was the only uncharted route in this floor so they went through.
*click.*
Hundreds of poison tipped arrows shot at the group at very fast speeds.
Using her vines fern managed to get everyone through unharmed.
"Surely treasure can't be this important!" Drake exclaimed.
"Maybe it's not just treasure." Jasper said.
They walked for a while before getting to a staircase. They walked down for a while before getting to the second floor (underground)