Geldam executive General Black met with the Great Leader of Shocker to discuss a merger between their two organizations. As part of their agreement, Black sent the Geldam kaijin Ganikomol to exterminate the remainder of the Shocker Combatmen so they could be replaced with stronger Gel-Shocker Combatmen.
Ganikomol was later encountered and defeated by Kamen Rider 1. However, the Rider was unable to prevent the merger of Shocker and Geldam.
Gel-Shocker was the result of the merge between Shocker and Geldam. The organization was made up mostly of Geldam members and kaijin, as the Great Leader had killed many of the old Shocker members and had all of Shocker bases demolished and the Shocker Combatmen exterminated and replaced with Gel-Shocker Combatmen. When Gel-Shocker was defeated by Double Riders, Geldan seemingly went down with it.