How hard is it to get an Elekid?

I don't know about its exact rarity but keep in mind it is part of the 5k egg pool, which is easily the most over-bloated of them.

I’ve hatched 16.. so I don’t think it’s rare. Just the RNG in the works.

I've hatched 19 Elekid out of probably 2000 eggs since gen 2, so I'd say the odds should not be exceptionally rare, but I haven't seen one in over 3 months, so yeah... RNG.

Now, contrary to what TheBiggestLeaf said, the egg group to which a species belongs does NOT determine how diluted it's odd are.

Each species, regardless of egg group, has a determined chance of being obtained through an egg. For example, you are twice as likely to hatch a Trapinch, Sudowoodo, Skarmory, or an Aerodactyl out of a 10km egg than you are to hatch any of the other (more-useful) species found in that egg group, simply because they have higher odds. 10km eggs are not that rare, but the species you will hatch from them will most-likely be one of the ones mentioned above because they have relatively-high odds of being obtained and just HAPPEN TO BE within the 10km egg pool.

In other words, the egg pool in which each species is found does not determine how diluted its chances are of being hatched, only how long it will take to walk it. So imagine egg types (except 7km eggs) only as distance-requirement shells, within the full pool of possible hatches on which each species has its own predetermined odds of being obtained through a stop/gym spin.

I've hatched a total of 44 Elekid, though I also tend to be incubating/hatching eggs frequently and in batches. In my personal experience, I wouldn't say they're that rare, but it all comes down to RNG and how frequently you hatch 5k eggs.

Not rare at all, hatched around 30 of them.

There was a time when they were as common as pidgey for me. However I haven't seen one in a while.