> Needs Ironman
> Any ethics (not xenophobe may easy your game though)
Step #1> Create a galaxy the size you want, the form you want, with maximum habitable planet (x5)
> Galaxy's ring form may help for efficient exploration
Step #2> Look for pre-sentient specie on any planet
> make sure that planet is inside your territory
> Once done, improve your empire until you have the society research "Epigenetic" be available.
> Research it
> Uplift the species
> Achievement complete !
That's all!
NOTE : The uplifted species have really interesting base modifiers and may be way better than your main species.
This guide is a quick and efficient way to obtain the achievement, but it can be completed through others means or during one of your casual games