Dr Gero - Genius Scientist #1

Thinking about it...

Android's 16-18 power systems, seem incompatible with the system's of 19-20.

That is, 19-20 have the capacity for Growth. And have a more powerful ability to essentially neutralize any ranged Energy based Attacks. (Which frankly speaking, 16-18 & Cell could have used.)

Maybe the Infinite Energy, requires stabilizing that the Absorption/Drain abilities disrupt.

Whilst 16-18 are seemingly completed with their full power realized... (even if 17 & 18 later demonstrated better techniques that may have been installed during building, or developed later.)

They don't seem to have been designed with a capacity for Real Growth beyond Refinement of Technique.

Whilst 20 comments on how 19's Energy Reserves(power) were increased beyond the orginal stock, after absorbing Goku's Kamehame.