Heavenly Legend.

Based loosely on the Monkey King legend, but set before he was sent to languish under a mountain for 500 years. The movie mainly focuses on two kids, a young Piggie (played by a fat kid with quite good makeup and a deadly fart weapon) and a young martial art master whose identity I didn't quite recognise. They get caught up in the affairs of The Dragon Princess Of The West Sea who rebels against her father by refusing to marry the Dragon Prince of The East Sea (or something like that!), and along with the Monkey King they have to fight various "fairies" (immortals) to ensure that justice is done.