For my son's 7th birthday, we had a Pokemon party. I found Pokemon pictures at various sites on the internet to use on the invitations and thank you cards. I made Pokemon balls out of plastic golf balls - painted them red and white.  We hid them in the yard for a Pokeball search.  We had a Pokemon walk with pictures of the different Pokemon characters taped to the floor in a huge circle - when the music (Pokemon theme song) stopped everyone had to stop on a Pokemon. We drew a Pokemon card out of a hat - whoever was standing on that Pokemon won a prize. I found instructions on the internet to make a Pikachu piñata - took a few days due to drying - but was not too difficult and turned out GREAT! The cake had Charizard drawn on it.  Party bags included Pokemon cards (of course). For a wind down, we watched the Pokemon movie on video until the parents arrived. My son said it was his best party ever!