The Patapon 2 demo features all the levels up to the Dodonga boss. It is obtainable for free in the Playstation Store, and can continue a Patapon 1 save file. When Level 1 Dodonga is defeated, he drops the Kingly Visage or the Lordly Hairpiece (depending on which version of the game you have). Both have the same effect, granting you total protection from status effects. Much like the Spear of Protection (which cannot be carried over from Patapon 1), this is the only way to obtain it. It is possible to obtain powerful Rarepons in this demo, by gathering rare materials from the Dodonga Patagate mission, and from the Ubo Bon minigame.
The Japanese Demo actually lasts longer since it also includes Mochichichi. The Demo was shortened for the European release.