Well, pink might not be his col-Rosie?

[Sorry, Cecil, your Clefairy is too busy banging her head against your shoulder to answer. Luckily, he actually trusts her judgement (though Leviathan is obviously the one with all the color matching talent).]

...Did you point the Pokédex at him since he hatched?

Goldenrod can help with that. They also have attacks with special effects, such as a particularly powerful poison.