Genesis Alpha One

There are 10 species, 2 per gas:
O2 - Human, Arachnoids
KOH - Kraul, Liquid
NH3 - Rok, Zeleny
N2O - Dekkah, Holo
HCl - Inferno, Mantiz

For this achievement you need to provide plants/a biosphere for each of the gases, then have at least one clone of each species and add whatever is missing to fullfil the requirements for a genesis. It does not matter what rank the clones are.

The lowest requirement for a genesis i have seen so far are 14 crew members of a specific gas. The mininum amount of crew you need for that achievement therefor is 14 + 8 = 22. So you will need a mininum of 5 crew quarters and, depending on the plants you can find, 2 to 3 hydroponics.

With the lowest level plants, you will need 7 (main) + 4 (off types), which result in 3 hydroponics. If you get 2 rank 2 plants of your main type (those which produce 3) you only need 2 hydros (2x3+4x2 =6 plants for main instead which totals to 10 slots in 2 hydros).

Travel the galaxy, search for a 14-crew genesis planet, build or adjust your ship accordingly, then clone the required crew. I'd suggest you use a checklist and the crew screen in any module to go through the list as the resource screen only shows how many crew members per gas you have, NOT their species.