Apparently nobody thinks about ditto in this situation. They can canonically take the form of a human (in both the game and anime canons), so that allows you to have sex with any person you want to.
i.imgur.com/UzvPXde.jpgThen I'd go for the standards, Gardevior, Lopunny, Hattrenne, Tsarenna and Pheramosa.
Though I'm not seeing Meloetta here. 'Sup with that.
Magikarp looks like it would be good at dick sucking.
I'd probably have sex with a Jynx, Bellossom, Mawile, Volbeat, Illumise, Milotic, Banette, Simipour, Leavanny, Whimiscott, Liligant, Gothitelle, Delphox, Florges, Gorgeist, Primarina, Mareanie, Lurantis, Tapu Lele, Tapu Fini, Magearna, Glossifleur, Alcreme, and Indeedee.