May accidently fuse pokemon and humans creating pokemorphs. May not. Take a risk. 
Resulting pokemorphs are the gender of the pokemon regardless of the human.
The mix of the two combines a balance of intelligence and instinct. With neither overpowering the other.
Physically, the result is an anthro pokemon with the secondary sex characteristics of both humans and pokemon.
If the player doesn't choose a pokemon, generate one based on their region and age. 
There is the option of a de-fuser