Generation Iii
Cute Charm
Infatuates on contact.
Detailed Effect
Whenever a move makes contact with this Pokémon, the move's user has a 30% chance of being infatuated. Overworld: If the first Pokémon in the party has this ability, any wild Pokémon whose species can be either gender has a 2/3 chance of being set to the opposite gender, and a 1/3 chance of having a random gender as usual.
Pokémon With Cute Charm
15 canonical Pokémon forms can have this Ability.

Clefairy
Clefable
Jigglypuff
Wigglytuff
Cleffa
Igglybuff
Skitty
Delcatty
Lopunny
Minccino
Cinccino
Sylveon
Enamorus Incarnate
Milotic 
Stufful 