For the decorations E wanted something other than balloons and so I was inspired to do something with hanging flowers. These tissue pom poms were the easiest thing and the results are terrific. They are also cheap to make and E could help with all but the cutting step. We made various size and color ones and hung them all above the party area. We recommend with this project to use heavy tissue paper with a wax side to the paper as the results are superior to that of a fine, light tissue paper.
Directions on how to make the Pom Poms can be found on the link below.
For the piñata I re-used an old piñata by taping up the bottom piece that was opened during a previous party cracking. I removed the decal it had previously but that also took of the front of the piñata flower so I cut out a new flower front from tissue paper and pasted it. For the decal I enlarged by 200% a picture of a Calico character head.
As there is no Calico Critter theme cake at any of the local bakery's, we made our own. We created a topper from a wooden round base (available at Joann's) some scrap gingham fabric, rick rack and hot glued on two Calico Critter characters. I suppose you could also ask your baker to paint Calico Critter characters if you don't want to make a topper.