The other colorbuddy can be obtained near the treeline at the top of the level. He is walking around in an evil bushling mask. To get him, you'll have to rain on the small bushlings to make them big and they will fight the big bushlings. Once they are all defeated, the colorbuddy will take his mask off!
The other puzzle piece is also available near the trees. In the area with the flamerocks, get one to blow fire at you and you can draw a wire from its fire to the pile of dynamite. It will explode and you can get the puzzle piece!