Magical Pokémon Journey
Pokémon PiPiPi Adventure is a ten-volume manga series by the Shoujo (girls') author Yumi Tsukirino, also serialized in the Shoujo manga magazine Ciao. The first seven volumes were translated into English by a group called Viz, but they have discontinued their translations.
The story of PiPiPi is about Hazel, a girl of about thirteen who has a major crush on a Pokémon trainer named Almond. In order to win Almond's heart, Hazel wants a love potion from a scientist named Grandpa, but there's a price -- he wants her to catch Pokémon for him!
This series chronicles Hazel's attempts to make Almond like her, as well as her friendship with several Pokémon she meets -- such as Pikachu, Clefairy, and Jigglypuff (Pikachu, Pippi, and Purin), for whom the series was named -- and her rivalry with Grandpa's granddaughter, Coconut.
Although PiPiPi is complete, Tsukirino is now writing another series set in the same world, entitled Pokémon Chamo-Chamo Pretty.