@Luna - Possibly, I'm not fully up to date on the mechanics with Luxury Balls though. Also, as I said in my answer, I haven't actually confirmed that a Pokemon that hatches from an Egg and that inherits a Friendship Ball from it's Mother, will have a base friendship value of 200, instead of 120, but it seems the most logical approach.
@sumwun - Yes, Cleffa's base friendship value is 140, so if you managed to catch one in the wild, in a Poke Ball other than a Friend Ball or Luxury Ball, it would have a friendship value of 140. While if you were to hatch a Cleffa from an Egg it would have a set friendship value of 120. Though I'm fairly certain Diamond, Pearl and Platinum are the only core games in which you can actually catch a Cleffa in the wild.
In all honesty I forgot all about the Luxury Ball, as I personally never use them.