The official Japanese website has revealed that a new Wifi event download the celebrate Pocket Monsters Movie 13 will be Satoshi's Piakchu. Starting July 15th, 2010 and ending on August 10th, 2010, players of the Japanese versions of Pokémon Diamond, Pearl, Platinum, HeartGold or SoulSiver can download Satoshi's Pikachu from Nintendo Wi-Fi Connection or Nintendo Zones in Japan like McDonalds.

Pikachu is level 50 and he knows the following moves: Volt Tackle, Iron Tail, Quick Attack & Thunderbolt.

Source: http://www.pokemon-sp.jp/news-sp/2010/07/0709_01.html