Obtain the Ice Missiles. When you encounter a Reptilicus (the four-armed lizard creatures on Bryyo), wait until he throws his boomerang at you. Immediately fire an Ice Missile at him. While frozen, the boomerang will come back and shatter the Reptilicus, earning you a green friend voucher.

In SkyTown, encounter a group of Steambot enemies. As a Morphball, use the Charge ability to glow and shoot through at least two or more Steambots, cutting out their legs. Doing this will reward you with another green friend voucher.