Core transplant has given me an idea to increase the numbers of rare Yukkuris: replace their cores with Feral Alice's ones to increase their sex drive. Increasing the numbers of every rare Yukkuri It is not desirable either because of the inherent hazards of certain types: Patchoulis and Youmus have an increased risk of not increasing their offspring because of their weak bodies, Utshuhos, Hinas and Medicines are a health/property risk, Yuyukos, Flandres and Remilias eat everything in their path.
I found a flaw in my former statement: core transplants between Yukkuris of different types result in both shape shifting and mind transfer, see post #4655.