Vermillion City is the third city a trainer will encounter. The city's Gym Leader is Lt. Surge, a professional-type Pokémon trainer.
Mr. String's Nicknaming Service
You can nickname your Pokémon by talking to a Purple Guy NPC in the PokéCenter. Even if you are not the OT, you can still rename the Pokémon in the newest update.
Traveling to Social Park
Talking to two NPCs will allow you to travel to Social Park. The left one will take you to a random Social Park server, whereas the right one will let you join a particular person.
Vermillion Gym is an-type Gym with Lt. Surge as its Gym Leader. Before you battle him, you must defeat another trainer named Youngster Rex.
Also, there is an NPC (based on Moderator Prindug) that wears a shirt with the text 'meme' on it. He explains that he is an unimportant NPC, and wishes he will eventually be important someday.