A genetic chimaera is an individual composed of cells with different genotypes, usually the result of two or more zygotes fusing during development. Generally, the chimaeric state is invisible outside of phenotypes that result in a visual or sexual difference.
A gynandromorph is an organism that displays mixed male and female characteristics, and is especially striking when genetic chimerism results in an individual with mixed markings due to sexual dimorphism. Gynandromorphs may be bilateral, polar, oblique, or mosaic in pattern depending on the distribution of male and female cells.
In this case, the specimen nicknamed Nidomonarch was originally observed as a Nidoran with bilateral asymmetry between the male and female coloring of that pokemon. They evolved to the next Nidorin@ form and eventually to the final Nidoking/Nidoqueen form. While chimaeric animals are often sterile, pokemon reproduce through manipulation of infinity energy and a chimaeric pokemon's mixed cells may not be an issue.
However, they were not observed to produce eggs or to donate energy to fertilize an egg, which may have been the pokemon's personal inclination: they instead evolved to their final form relatively quickly and served as a protector of the warren for many years. It is also possible that the pokemon's mixed appearance or behaviors may have led to social barriers to mating.
Gynandromorphs are found in our world, with many striking examples found in the insect world as well as among birds. It's possible for mammal and human chimaeras to form and incorporate cells from male and female zygotes, but the results typically go unnoticed due to how the embryo develops.
Please note that many of the terms used in this description are specific to zoology and entomology and are not appropriate to describe human beings.
Gaiien Region: Chimaera Pokemon: Nidomonarch
by Keleri