East of Doxy Marigold is a Hotshot Trainer guarding an entrance to an alleyway. After defeating him, he will allow you to pass, where you can find more trainers to battle, some Pokémon to catch, and a Super Potion. During Rain, a Tynamo will appear here.
North of the first entrance from the Opal Ward is a man asking for money. After giving four payments of 50, he will leave and let you pass through to a house holding a traumatized Espurr. If you have PokeSnax in your bag, the Espurr will react to the scent and join you.
In the hotel next to the entrance to the underground Railnet, a girl is concerned about her Kricketot's ill state. The Bug gym leader Shelly is called in to look it over, and she declares that it isn't sick, it's just extremely lonely. As its current owner cannot give it the attention it needs, the two suggest the player look after it instead.
Whismur cannot be obtained in the Peridot Ward after beating Julia's Gym
Just past Casanova Darin is a dumpster that holds a Gulpin, as well as a house that holds a Whismur. The Whismur will react to the PokeSnax in your bag, but unlike the Espurr, it will attack, so it must be caught in-battle rather than be received.
After defeating Julia, return to the train station and speak with the man nearby, who has begun his search for a new home. Return to the house that had held a Whismur, where the landlord has returned. He asks you to send the man in, and after returning to tell the new renter this, the man shortly moves in. He gives you his old Onix as thanks.