I wanna know more about the lore 📝.
((Gonna talk a bit about how Pokemon genetics work in my PMD variation))
When it comes to pokemon children, most of the times the species and traits of that pokemon will be passed down from the mother. If you have a mother Gigalith and a father Revavroom, the child will most likely be a Roggenrola. While it is possible for that child to be a Varoom, it's less likely to occur. Unknown gendered pokemon can still have children like any other pokemon, but the child will have a much higher chance to be the gendered Pokemon's species. Between two unknown genders, it's an even 50/50 split chance.
But what traits show up in a pokemon is not as simple as what species they are. For the traits of the other partner can show itself on the child. Going back to the Gigalith and Revavroom example, if the child is indeed a Roggenrola, that roggenrola may take traits from their Revavroom father. These can be smaller changes like gaining the purple poison pattern of there body, a complete pallet swap to be more similar a varoom. More drastic changes, such as gaining the steam pipe or their feet becoming the wheels. Basically, the most common form of traits a pokemon will get from the other parent will be uncommon colors/patterns or small bits of extra physical additions not normally found in that species.
The biggest changes come in if a child pokemon gains the powers and/or typing of the other pokemon. The smallest example of this bigger change is a pokemon being able to learn moves from the other Pokemon's move pool.
This theoretical roggenrola child has the chance to gain many of the revavroom's fighting traits. They can gain Varoom's typing (it can show up as replacing the original typing or adding onto it), or one of it's abilities. Having any of these changes is guaranteed to come with a drastic change on the child pokemon's normal species anatomy.
For another example of how a pokemon can show the traits of the parent, look no further than Javi himself and his brother (yes he does have a brother Javi just never talks about him)
They are brothers, yet still look drastically different due to what traits show up on each of them. Their parents are a Grafaiai mother and a Drizzile father. Briar got a lot more of his father traits, in the form of his typing and posture (fun fact: the normal type is the most likely type to be replaced in a mon if there is an option of two. Normal is almost the most common type to be lost completely when a child is born from different species parents). While Javi got virtually none of them.
One of the rarest genetic changes is a "Fusion", a pokemon that is a near 50/50 split of both parents. Where it's near impossible to tell what species is more dominant. They do most often share one of each type of both parents and have a very diverse move pool of both parents.
Final note to end this off. If the parent pokemon are evo mons, then the child will always be the pre-evo. Including the traits they gained from the other parent. A child will never get traits of fully evolved of the other parent. Evolution will evolve those gained traits along with them. If the main species can't evolve, then the child will not get the fully evolved traits of the less dominant species. Evolution with these pokemon is never cut and dry, but usually it is dependent on what the main species is. And two pokemon do have to be in the same egg group to have a child. It is wildly rare to have a pokemon be born from parents in two different egg groups, but has happened.
