Had a little idea for the sex scene for Xerneas and Yveltal. Since Xerneas keeps making life energy and radiating it, it is very difficult for anyone to die that is not an instant kill attack. So she never really learned to hold back her strength so when she has sex with the MC she can slam her entire body down and almost destroy his pelvis but it heals instantly since they would be directly touching and connected and then she would continue to literaly pound him lost in the pleasure of becoming pregnant. Yveltal would be the opposite since with one wrong move she would have a corpse and all the other legends would go after her. She would want it to last as long as possible so she would see him as fragile to her power and she would not find anyone else who would want to lay with death.