I think that it’s ok to be sexually aroused by Pokemon. More so, I think it should be encouraged in the games and anime, and GameFreak should lean into it.

Firstly, some Pokemon are shown to be much smarter then humans. Kadabra has been said to have an IQ over 5000, which is gigantically more than the definition of an animal, which have an IQ between 0 (Worms and Fish) and 65 (Apes and Octopus). Thus, they are smarter then needed to be able to give consent.
Secondly, the argument could be made they are not as empathetic as humans, and thus can't give consent. This is proven not to be true numerous times in the anime, by watching Meowth. In Season 2, Episode 16 of the Pokemon show, it is established that he is no smarter or different then regular Pokemon, he simply learnt to walk by watching a dance rehearsal and later learnt English through a picture book. Throughout the following seasons, it’s shown how he schemes, laughs, cries and even at points, deceives people into thinking he is a human (in order to steal Ash's Pikachu of course).
And the last piece of damning evidence - a folk tale in the Canalave Library (Pokémon Diamond and Pearl) literally STATES that humans used to marry Pokémon. This was removed in the English translation. Gamefreak, if you wanted us to fuck Pokémon, just say it.

Conclusively, Pokemon aren't animals. They are intelligent, with empathy and kindness, and should be treated as equals. Denying them the right to have sex with humans removes their freedom, which is racist, and frankly, unamerican.