Suddenly,a Pidgyotto scatches you in the face, then flies off.
Suddenly, the back of your shirt feels wet. You see a Metapod behind
you. Obviously, a Caterpie was being attacked by a Pidgyotto while
evolving. You saved the Caterpie by transporting in the middle of the
battle. You paid for it by getting scratched in the face, and getting
some of Caterpie's String Shot formula on your back. The formula was
being used by Caterpie to envelope itself in a cocoon. Now it is a
Metapod.