[I am assuming I have permission to create this thread]
BRIEF INTRODUCTION TO WHAT CONSTITUTES A SPECIES IN THE REAL WORLD
It initially appears obvious what a different species is. A dog cannot produce offspring with a cat, a horse only makes infertile offspring with a donkey, and so on. This works for us most of the time. It doesn't, however, work very with to classify plants, as a large majority if not all plants can breed and produce fertile offspring with other plants that are not considered the same species. This definition also does not hold up well when classifying protists and everything smaller than that, as a lot of micro-organisms reproduce asexually. In these cases biologists assign arbitrary borders to what constitutes a species based on a set of shared characteristics of that population.
AS APPLIED IN POKEMON
In pokemon, we have Egg Groups, which is a group that all of the members within can interbreed to produce fertile offspring. This looks encouraging at first, but there are a lot of gray areas, such as the ability of Ludicolo to breed with Tropius or Mantine but the inability of Tropius to breed with Mantine. So I'm curious to see what the community thinks about what defines a pokemon species. The most obvious method of separating evolutionary lines is more or less equivalent to the plant system of species classification - a set of arbitrary characteristics shared by the population. This may be the best that we can do, but maybe not!
-Slowpoke's evolutionary line and Squirtle's are both in the Water 1 egg group and the Monster egg group, and therefore have an identical set of possible breeding partners. Does this make them the same species?
-Since there are plant-classification-like pokemon (Ludicolo-Tropius-Mantine example), animal-classification-like pokemon (Slowpoke-Squirtle), and asexual-classification-like pokemon (all asexual pokemon such as Magnemite), should there be a variety of species classification systems used in combination?
-Cranidos can breed with the Monster egg group even though it was revived from a fossil thousands of years old. How is it possible for the species of "breeding only within the Monster egg group" to have developed such diversity in appearance and characteristics and yet apparently not have evolved for however long Cranidos has been extinct?
-Is Relicanth the probable common ancestor of Remoraid, Octillery, and Alomomola, as all share the same combination of Water 2 + Water 1 egg groups?
-Is the origin of Luvdisc as a deformed mutant of Alomomola, since it retains the ability to breed within Water 2 but lost the ability to breed with Water 1? Additionally, if a Luvdisc breeds with Alomomola, the offspring may relearn some of the abilities lost by its Luvdisc parent (egg moves)
Is it possible to use this data to construct a pokemon phylogeny tree?