As an example, allowing my Lucario to learn Nasty Plot.
No, the Move Relearner does not teach preevolution moves that the Pokemon missed by evolving too early. For example. a Growlithe caught at level 18 and immediately evolved to Arcanine cannot learn Leer or Ember. The only moves available for it would instead be the ones available to Arcanine for leveling up (including Thunder Fang, which is not available to Growlithe, and Extreme Speed, which Arcanine learns naturally at level 34).
According to Bulbapedia:
Move Reminders are restricted to teaching a Pokémon only moves that its species can learn; they cannot teach moves exclusive to an earlier evolution. In particular, many Pokémon that evolve by evolutionary stone have a very restricted set of learnable moves in their evolved forms compared to their unevolved forms. For example, Eevee can learn Take Down by leveling up, but none of its evolutions can; this means that an Eevee of level 25 or higher could be taught Take Down by a Move Reminder, but a Vaporeon or other Eeveelution of the same level could not.
Exceptions to this are Pokemon hatched or spawned in or beyond Gen VI that had once known special moves, such as egg moves, event-only moves and special moves obtainable by the ORAS PokeNav function.
However,
Starting in Pokémon Sun and Moon, the Move Reminder can also teach moves a Pokémon has yet to learn by level up.
Assuming I read it correctly, if your Riolu isn't yet Level 47, it could still learn Nasty Plot through the Move Tutor. That's interesting.
Hope I helped. :) Source
