It doesn't matter if you've only played up to the point where you set the clock, or if you've beaten the Champion. just load the mon into PKHeX then set it into an empty space (read onwards if you don't know what that means) First of all, you'll need a Pokémon game with a save. If you'd rather not bother generating your own mons, there is an event database here which contains pre-packed mon files that PKHeX can load and write into your save.
