Chansey is a Normal-type Egg Pokémon in Pokémon Brilliant Diamond and Shining Pearl that evolves into Blissey, an excellent support Pokémon with high HP and Special Defense at Base IV. However, before any evolution occurs, Trainers will first need to acquire Chansey or its base form, Happiny. One of the easiest ways to get Happiny is by going to Hearthome City and speaking with the Hiker NPC in Diamond and Pearl next to the city's eastern exit. He will offer an egg that he found at the Daycare, and the player can walk until the egg hatches into Happiny.
On the other hand, Trainers can encounter a wild Happiny or Chansey via the Walking method in Pokémon BDSP. Within the Trophy Garden, players will have a fair chance of finding a Happiny or Chansey. Trainers can also travel to Routes 209 and 210 to encounter a wild Chansey at a common spawn rate. Keep in mind that the time of day does not matter, as Happiny or Chansey can be found during Morning, Day, or Night.
Once players have caught Happiny, they can evolve it into Chansey by letting the Pokémon hold an Oval Stone in Pokémon BDSP during the daytime. If Trainers already have Chansey, they can evolve it into Blissey by raising its Friendship Level. To check how high or low a player's Friendship Level is with Chansey, they will need the Friendship Checker app for their PokéTech. To unlock this app, speak to the NPC with long brown hair within Eterna City's Pokémon Center. After some dialogue, she will give players the Friendship Checker.
Chansey Evolution Guide in Pokémon BDSP
Raising a Pokémon's Friendship Level in Diamond and Pearl isn't very difficult but can be confusing if players don't know how it's done. Fortunately, there are several definite ways that Trainers can raise Chansey's Friendship for its evolution. First and foremost, give Chansey a Soothe Bell, a unique "holding item" that increases Happiness more quickly, resulting in an enhanced Friendship leveling rate. One location where players can obtain a Soothe Bell in Pokémon BDSP is the Pokémon Mansion on Route 212. Inside, head into the second room on the left, speak to the maid NPC, and she'll offer a Soothe Bell for free.
A few other ways players can boost their Friendship Level with Chansey are by walking with the Pokémon, feeding it vitamins, or treating it with a massage in Veilstone City. Yet, the most effortless way to gain Friendship is by winning battles with Chansey in the Trainer's party. Once Chansey reaches a high enough Friendship Level, it will evolve into Blissey.
Pokémon Brilliant Diamond and Shining Pearl are available on Nintendo Switch.