A number of Pokémon in Brilliant Diamond and Shining Pearl don’t evolve through the straightforward level-up method. The psychic-type Pokémon Chingling, in particular, requires two additional conditions to be met. In order to evolve into Chimecho, you must both have a high friendship level with your Chingling. Additionally, Chingling can only evolve at night.
In Pokémon Brilliant Diamond and Shining Pearl, “night” is whenever it’s dark outside in-game, which runs from 8 PM to 3:59 AM on your Switch’s time settings. Theoretically, you can go to your Switch’s “Date and Time” settings, desynchronize it from the internet, and manually change the game to be night. But who would do that, right?
However, the time of day is the easier half of Chingling’s evolution conditions. You also need to have high friendship with your Chingling. Ways to deepen your bond with your Pokémon include keeping it in your party, not letting it faint, taking it out of its PokéBall for a walk, and feeding it Poffins and vitamins. You can tell if your friendship is high enough by checking to see if your Chingling shows two hearts in the Pokétch’s Friendship Checker.
From our experience, Chingling actually evolved before showing those two hearts on the Friendship Checker. However, the Chingling had been in the party for a long time without break, had consumed vitamins, and had been walking quite a while. It was not as much of a stickler as Budew, which suggests the Pokémon’s personality type may also favor into how easy it is to evolve them.