If a Poliwhirl was tested beforehand and his Fighting-type potential turned out to be undeveloped, then he was not yet suited to evolving with a Water Stone;
if a particular Poliwhirl was found to have very poor Fighting-type potential, they could also change course and use a King's Rock to evolve him into Politoed (Politoed).
The same principle applied to Eevee. They could test his potential-his aptitude for types and energy-in advance, then choose a suitable type for his evolution.
"This Qwilfish is normal."
"Understood."
Word came back from the temporary command post over the radio: the Qwilfish Shen Qi had scooped up did not have the potential for a compatible combination of Dark- and Poison-type energy.
Ordinary Qwilfish were Water/Poison types. Their Poison-type potential was obvious, but if their Dark-type potential could not match and work in tandem with it, they could not evolve in that direction.
It was like how Prinplup (Principe Penguin) was a pure Water type. Even if that potential had been properly developed, if its Steel-type development had not caught up and harmonized with it, it could not evolve into its final form, the Steel/Water-type Empoleon.
"All right."
Shen Qi released the Qwilfish back into Lake Valor, his mindset already very steady.
It was his sixth day at Lake Valor. When he first started rowing out to scoop up Qwilfish, Shen Qi had been a little clumsy, and very excited whenever he succeeded.
Now his technique had become practiced... which was not actually a good thing. It meant the first survey cycle was nearly over, yet they had not discovered anything.
After all, Hisui Pokémon had begun gradually disappearing hundreds or thousands of years ago. The weaker ones had been replaced by their modern forms;
Overqwil clearly had greater potential than modern Qwilfish, so its