To be honest, It'd depend if it were sentient. Like, does the Pokemon know it's a Pokemon? If it does, can it reciprocate love, can it even determine what love is? The fact that I'm even talking about it makes me sick, but actually think about it. Would you fuck a human that has the ability to determine it is a human. Sure, humans can decipher love, but Pokemon can too, seeing as Ash and Pikachu can determine love for each other. Should they not be able to fug?