All of my Gatchaman synopses-- about half of Gatchaman I, and all of Gatchaman II, are available below:

Gatchaman I Synopses by Alara Rogers, Pat Munson-Siter and James Long; includes brief descriptions of the BOTP versions of the episodes

Gatchaman II Synopses by Alara Rogers, Pat Munson-Siter, and translated by Alara Rogers from OUT Magazine; includes all Gatchaman II episodes