Head for Mt. Moon!

Leaving the Pokécenter, you travel east, towards the outskirts of town. You see a road leading to a mountain path, full of eager Trainers and grassy areas where you could find new Pokémon.

Beyond them all, according to the map you memorised in the Pokécenter, is Mt. Moon. It should be a relatively short spelunk through the cave to bring you out near Cerulean, the reportedly beautiful waterside city.

Setting off, you pass a young man, about your age, dressed all in green. He whistles as you go by, gaining your attention.

"Heya toots, you're a Trainer, right?" He asks, eyes flicking down to scope out your bare legs.

"I guess so." You say, a little irritated by the unsolicited interruption.

"Brock's looking for hot new cumdum- Uh, I mean tough new challengers! Come with me!" The blonde man says.

Seizing you by the arm, he pulls you back towards Pewter City, and the Gym.

You're so gobsmacked by the kid's impetuousness that by the time you've recovered, and are preparing to let Pikachu out to taze the asshole, you're standing outside the Gym.

"Here we are! Tell Brock who sent ya!" The Leader's crony says, shoving you through the double doors.