After you visit Solaceon Town, you can continue north through Route 210 on your way to Veilstone City.
Catch Pokémon
In Route 210, you can catch Bonsly (Shining Pearl only), Chansey, Geodude, Kricketune, Mime Jr. (Brilliant Diamond only), and Ponyta.
Battle Trainers and Find Items
Northeast of the entrance, there are berry trees.
West of there, you can battle Rancher Marco, who has a level 18 Aipom, a level 17 Girafarig, and a level 19 Psyduck. You get 952 Pokédollars for winning.
If you go up the nearby hill where the Jogger is running back and forth, you can use the northeast stairs and talk to the trainer to get some TM51s, which teach Roost.
If you go back and use the northwest stairs, you can go north and battle Ranchers Ava and Matt, who have a level 21 Glameow and a level 21 Stunky. You get 5208 Pokédollars for winning.
West of there, you can go up the slope and down the stairs to battle Twins Teri and Tia. They have a level 21 Clefairy and a level 21 Pikachu. You get 1848 Pokédollars for winning.
North of the twins, you can battle Pokémon Breeder Kahlil, who has a level 18 Pichu, a level 17 Happiny, and a level 19 Pikachu. You get 1088 Pokédollars for winning.
North of the Pokémon Breeder, there is a Great Ball.
East of that, you can battle Pokémon Breeder Amber, who has a level 19 Cleffa, a level 18 Happiny, and a level 17 Clefairy. You get 1152 Pokédollars for winning.
Southeast of that Pokémon Breeder, there is a Honey tree.
West of the Honey tree, there is a hidden Great Ball in the grass.
To the north, you can go into Café Cabin. Inside, you can talk to the upper left trainer to battle Collector Fernando, who has a level 17 Mr. Mime, and two level 20 Mr. Mimes. You get 1520 Pokédollars for winning.
Talk to the trainer on the other side of the table to battle Collector Edwin, who has three level 19 Sudowoodos. You get 1444 Pokédollars for winning.
Talk to the person to the right of the Collectors to battle Waitress Kati, who has a level 22 Clefairy. You get 968 Pokédollars for winning.
Talk to the person at the counter and you can buy Moomoo Milk.
Go back outside. Since the north path is blocked, you have to go east to Route 215.