Could work for all three. For Solgaleo and Lunala it could anchor them to him since they had his dick in them and can be the reason they evolve to the form since they just need a little bit more mass to start the evolution in their respective areas. MC could be sent two Cosmoem or two Nebby from diff dimensions but the same personality and just take each to a location with the proper energy just need an orgasm to start the evolution. The two would be needed to end the eclipse in the region and get the last legend. Plus it could be the reason why the MC's dick starts making the energy that Necrozma needs to calm down.
For Urshifu it could lead to a way that allows the MC to manage the dark trait she gains after evolving.
This may also be used for Poipole that becomes Naganadel of the Ultra beasts if wanted.