This is a complex process, at least the way I did it, but I will try to explain my method.
You will need to unlock the Mutator – I think this is unlocked with the Tek Cloning chamber. The Mutator forces every hatched Dino to mutate, and you can also mutate the dino’s 3 times ( need 3 mutators) . Just before the babies are hatched or dropped, activate each mutator ( lasts about 5 minutes) You will need a lot of element, but that is easy to get on Genesis 2, with a Mantis.
I usually mutated 4 stats, Health, Stamina, Melee and Weight. To get level 900 you will need 4 stats.
I mutated the Males, and had a group of unmutated Females.
Female Breeder + Male breeder = baby with mutated attribute
For Strenght you would do this ( assuming Male has a strength of 30 )
Base Female + base Male S30 =baby Male – Strenght 33
Base Female + Male S33 = baby Male S36
Base Female + Male S36 = baby Male S39
Do this 20 times
Then you breed to combine the 4 mutated attributes.
You can create levels in you base, and if the male is in the center, you can have 3 layers of females. The problem is the mutation is random, so you may not get your mutation, every time. I tried for 25+ females for each stat, and would almost get the mutation ,I wanted, every time.
The mutator can also change, the sex of your dinos, so if you only have a mutated female, you can change it to a male.
As this is a timely process, I usually tried to mutate multiple dinos.
Devices to help automate the process
Hatchery – pick up eggs and hatch them
Soul Terminal – pick up unhatched and bred dinos
-Also used to see the stats of the babies
Nanny – feed the babies - they eat a lot
Cloning chamber – speeds up the process
I have now confused you, but the internet has some good videos, that explain with video.
Good luck
Pinto