Do you literally just breed a Pokemon with one that has an egg move it can learn or does the Pokemon need to learn it, for example, I wanna teach my Chansey Aromatherapy, do I need a Roselia that knows it or can it be any Roselia?
The main purpose of breeding is usually to obtain a Pokémon that knows certain moves. If the male Pokémon knows moves that the baby Pokémon is capable of learning, it will know them when it hatches from the egg. This is a good way to reuse TMs that you taught a Pokémon and cannot re-obtain in another way like buying. The baby will know any move that it learns at level 1. If both parents know a move that the child would learn by level up, the child will also know it upon hatching. Furthermore, there are some moves Pokémon can only learn by breeding - these are called egg moves, and are listed in our Pokédex alongside the other moves. In most cases, a Pokémon in the same egg group learns the move by level up and can pass it on by breeding, but sometimes you need to chain breed from one Pokémon to another to another. If there are too many candidate moves that the baby can learn, they follow this precedent, with each new move overwriting previous ones: • Level 1 moves. • Moves that the child learns by level up, if both parents have them. • Any compatible TMs, HMs and move tutor moves known by the father. • Any egg moves known by the father.
That is taken from this section of the DB, under "Game Mechanics". The link provided also explains IV breeding, Egg Groups and more.
