All types of Molly will mix and breed and you will get some cool colour variants when the babies grow. This is the same for mixed guppies, mixed platys, mixed swordtails and mixed endlers.
Endlers will readily breed with guppies also, as can platys and swordtails. Some people say an endler-guppy cross is ugly mind and you probably won't be able to sell them to LFS.
All you need to do is choose one species, your favourite from the list, and get perhaps one male and two or three females (to stop him chasing one female and tiring her out).
After that keep them well fed and water changes up to scratch and within six week max you will have your first lot!
Just my opinion but it may help you choose. I find swordtail fry have better survival rate if left in main tank as they are born bigger than other fry, endlers will rarely eat there babies like the other species and mollys usually drop a lot more fry regularly (30+).