The official Japanese website has announced a new Nintendo Wi-Fi Connection event for the Japanese versions of Pokémon Diamond, Pearl, Platinum, HeartGold and SoulSilver. A level 50 Manaphy (マナフィ) will be available from August 14th, 2010 to September 12th, 2010. McDonald's is also advertising the event and the Manaphy will be available at Nintendo Zone locations across Japan.

Manaphy knows the following moves: Aqua Ring (アクアリング) , Water Pulse (みずのはどう), Water Sport (みずあそび) and Heart Swap (ハートスワップ).

Source: http://www.pokemon-sp.jp/news-sp/2010/08/0806_01.html