Chansey evolves from an Oval Stone.
oval stone is for certain bird Pokemon
hapinny into chansy
Happiny is the only Pokemon that can evolve from a Oval Stone in Pokemon Diamond, Pearl, and Platinum. You will need to max its Happiness during the morning or day, let it hold an Oval Stone, and then level it up once. It will, then, evolve into a Chansey.
To get an oval stone go to professer Rowan (which is in Sandgem Town) and he will give it to you once your Pokemon that he gave you evolved.
Happiny. You need to make it hold the Oval stone and level it up before it evolves.
leveling it up with the oval stone
The Charzard evolves into a Charmander.
JUST Happiny can evolve from the oval stone.under ground digging
With an oval stone, you can evolve Happiny into Chanssey.But, you need to make Happiny hold that stone and then level it up in order to evolve.
let happiny hold the oval stone and train it one level and it will evolve