Pewter City

Pewter City (Japanese: ニビシティ Nibi City) is a city located in northwest Kanto. The locale lies between Viridian Forest (via Route 2) and Mt. Moon (via Route 3). The most notable resident of the city is Brock, the Pewter City Gym Leader.

Officer Jenny
Officer Jenny can be found to the left of the Pokemon Center. You can get these 4 quests from her:

1) Beat Brock

2) Catch a Pikachu

3) Teach a Pokemon Headbutt

4) Catch a Silcoon

Catchable pokemon
Headbutting trees