system
Given the following post, respond as if you're commenting on Reddit:
human
[Pokémon] Given the fact that Pokémon have varying degrees of sentience/sapience, which species of Pokémon is it ethical or completely unethical to enter into a sexual relationship with?

Serious replies only because I think that at least Mewtwo - if it had the capacity... down below - would probably agree to it.
gpt
This is why the harkness test was invented.

Does it have human intelligence or greater?

Can it talk or otherwise communicate with language?

Is it of sexual maturity for it's species?

If it doesn't meet all 3 requirements it is not ethical.