These Pokémon are only obtainable through breeding:
* Magby: Breed a Magmar with a Pokémon holding the Everstone.
* Smoochum: Breed a Jynx with a Pokémon holding the Everstone.
* Elekid: Breed a Electabuzz with a Pokémon holding the Everstone.
You will not find these Pokémon in the wild, nor will you receive another egg with them after obtaining one.
If you find an egg that you're certain should contain one of these Pokémon, it could be a glitch or a misunderstanding.
It's important to note that Pokémon eggs have a chance to hatch into a different Pokémon than the one you expect. This is due to the influence of the Hidden Power stat.
If you are certain you have an egg that should be one of these Pokémon, and you're getting something different, you might have been unlucky with your egg hatching or a glitch might be involved.