Elekid is good but it it's not going to doom UU. Even with LO it lacks the base power to take out many pokes and that's why it's dropped to such a low usage percentage despite have good physical coverage and amazing speed. I'd say it's A rank material.
Edit: It's nice to counter bird spam cause I've seen teams with tailow + dodou and those hit hard.
Purloin and sash solosis are still good without omanyte around. Scarf elekid, on the other hard, is very niche for shell smashers as would be hp grass on water types.
Elekid doesn't "counter" bird spam, it actually can't switch in on either without Eviolite (and Facade / Return / Knock Off + Quick Attack still KOs that iirc)