Krillin wanted to use it to help Android 17 and 18 go back to how their lives were before they were turned into Androids. Krillin asked Shenron to turn 17 and 18 back into humans, a gesture that caught the attention of 18 herself.
What is the power level of Android 18?
According to the board game Dragon Ball Z: The Anime Adventure Game Android 18 has a power level that clocks in at an insane 30,000,000. To put that into context, Goku had a power level of about 1.2 million at the end of the Frieza Saga.
Why does cell need 17 and 18?
The rules of Cell were pretty clear. He needed to absorb Androids 17 and 18 to achieve his perfect form. Since the word absorb means to assimilate, it was believed that the Androids would cease to exist.