https://pokemongo.gamepress.gg/pokemon/370
The Emerald Pokedex entry states that giving a Luvdisc is a way to express one's feelings of love. Placing this Pokemon in the gym of a mortal enemy may yield... unexpected results.
The Sapphire Pokedex entry states that any couple that comes across a Luvdisc is promised a loving relationship that never ends. Luvdisc may make playing in water biomes a great first date, perhaps with that mortal enemy from earlier? ( ͡° ͜ʖ ͡°)