>>31893939>All Pokémon who can learn TMs and have genders can learn Attractexcept Nincada, Ferroseed, Ferrothorn, Larvesta, Volcarona, and
Oranguru.
Shedinja is genderless, so they didn't want to give Attract to Nincada who evolves into it, even though they clearly don't care about that sort of thing these days.
It's a meant to be a joke with Ferroseed and Ferrothorn. They're too spiky to love.
With Oranguru, I guess because it's so similar to humans in appearance and behavior, they didn't want any, "Oranguru used Attract!" jokes? It would have drawn less attention if they just let it learn Attract, but whatever....
Volcarona is Dumbledore. Dumbledore is passionately romantic, but becomes drunk on love if he ever allows himself to fall for someone else. Thus he chooses to remain alone and celibate so that he can focus on helping others. 