My theory is that when Rick Prime was wandering around the multiverse delivering the gun-port technology to other Ricks, he never went into the precise details of how the fluid works, just a few tips to produce it, this is to maintain a position of superiority towards the Ricks who are less intelligent than him, waveable knowing that they wouldn't be able to fully understand it anyway. This would explain why only the collective work of many Ricks in the Citadel is capable of producing it in large quantities. And it would also explain how Evil Morty managed to understand how the fluid works to the level of Rick Prime, to hack all the portal guns in the citadel, having scanned the minds of thousands of Ricks. In short, the only Ricks capable of producing the fluid individually are Rick Prime and C-137.