How do you evolve Pichu in Pokemon Platinum?

Pichu evolves into Picachu when it is levelled up with a happiness rating of at least 220 (indicated by two large hearts on the Friendship Checker Pokétch App.). You can increase a Pokémon's happiness by levelling it up, walking 256 steps with it in your party, using an item on it and getting it a massage in Veilstone City or the Resort Area.