How do Pokemon get level-up moves that are learned before or after their evolution?

Question

in the pokedex pages on this site, I noticed that some Pokemon are shown to learn moves after the level when they evolve, or evolved Pokemon have moves that are learned before they evolve. how exactly does this work?

Answer 1

You could chose not to evolve a Pokémon (or have it hold an everstone) and level it up past the level it evolves to teach is a move. Or (in Gen 7) you can use Heart Scales to teach the Pokémon those moves. These moves are generally there so that you can learn a move an evolution has before evolving, or sometimes a move its next stage can't learn. :P

As for evolved Pokémon that learn moves before they should have evolved, this may be for two reasons. Reason one being that you can relearn moves from a previous evolution with a Heart Scale (or a move that its prevo can't learn), and reason two being that sometimes the devs have a NPC with an evolved Pokémon or a wild evolved Pokémon that is encounter-able before it's evolution level, so it needs moves that it can use. Actually, for this reason, every Pokémon has at least one move that it learns at Level 1 (so that a Pokémon will never be generated with 0 moves). :P

Source: Stat EXP

Hope I Helped!